View source for Leukemia

{{Short description|Blood cancers forming in the bone marrow}}
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{{for multi|the journal|Leukemia (journal)|animal diseases|Leucosis}}
{{Use dmy dates|date=January 2020}}
{{Use American English|date=August 2024}}
{{Infobox medical condition (new)
| name = Leukemia
| synonyms = Leukaemia
| image = ALL-AML.jpg
| caption = A [[Wright's stain]]ed bone marrow aspirate [[Cytopathology|smear]]s from individuals with [[B-cell acute lymphoblastic leukemia]] (left) and [[acute myeloid leukemia]] (right). Myeloid leukemia cells are usually larger, contain prominent nucleoli, and specific, but not mandatory, cytoplasmic inclusions – [[Auer rod]]s (purple needles).
| field = [[Hematology]] and [[oncology]]
| pronounce = {{IPAc-en|l|uː|ˈ|k|iː|m|iː|ə}}<ref name=pronunciation>{{cite dictionary|url=http://www.merriam-webster.com/dictionary/leukemia|title=Leukemia |date=30 May 2023 |dictionary=Merriam-Webster }}</ref>
| symptoms = Bleeding, [[bruising]], [[Fatigue (medical)|fatigue]], fever, increased risk of infections<ref name=NCIBook2013/>
| complications = 
| onset = All ages,<ref name=NCISnap/> most common in 60s and 70s.<ref name=SEER/> It is the most common malignant cancer in children, but the cure rates are also higher for them.
| duration = 
| causes = [[Heredity|Inherited]] and environmental factors<ref name=Hut2010/>
| risks = [[Smoking]], family history, [[ionizing radiation]], some chemicals such as [[trichloroethylene]], prior chemotherapy, [[Down syndrome]].<ref name=NCISnap /><ref name=Hut2010 />
| diagnosis = [[Blood test]]s, [[bone marrow biopsy]]<ref name=NCIBook2013/>
| differential = 
| prevention = 
| treatment = [[Chemotherapy]], [[radiation therapy]], [[targeted therapy]], [[bone marrow transplant]], [[supportive care]]<ref name=NCISnap/><ref name=BCDtargetedTherapy/>
| medication = 
| prognosis = [[Five-year survival rate]] 67% (U.S.)<ref name=SEER/>
| frequency = 2.3 million (2015)<ref name=GBD2015Pre/>
| deaths = 353,500 (2015)<ref name=GBD2015De/>
}}

'''Leukemia''' ([[American and British English spelling differences#ae and oe|also spelled]] '''leukaemia'''; pronounced {{IPAc-en|l|uː|ˈ|k|iː|m|iː|ə}}<ref name=pronunciation/> {{respell|loo|KEE|mee|ə}}) is a group of [[blood cancer]]s that usually begin in the [[bone marrow]] and produce high numbers of abnormal [[blood cell]]s.<ref>{{cite web|title=Leukemia|url=http://www.cancer.gov/cancertopics/types/leukemia|website=NCI|access-date=13 June 2014|url-status=live|archive-url=https://web.archive.org/web/20140527085758/http://www.cancer.gov/cancertopics/types/leukemia|archive-date=27 May 2014|date=1 January 1980|quote=Cancer that starts in blood-forming tissue, such as the bone marrow, and causes large numbers of abnormal blood cells}}</ref> These blood cells are not fully developed and are called [[Precursor cell|''blasts'']] or ''[[Precursor cell|leukemia cells]]''.<ref name=NCIBook2013>{{cite web|title=What You lNeed To Know About Leukemia|url=http://www.cancer.gov/cancertopics/wyntk/leukemia/page2/AllPages|website=National Cancer Institute|access-date=18 June 2014|date=23 December 2013|url-status=live|archive-url=https://web.archive.org/web/20140706152110/http://www.cancer.gov/cancertopics/wyntk/leukemia/page2/AllPages|archive-date=6 July 2014}}</ref> Symptoms may include bleeding and [[bruising]], [[bone pain]], [[Fatigue (medical)|fatigue]], [[fever]], and an increased risk of infections.<ref name=NCIBook2013 /> These symptoms occur due to a lack of normal [[blood cell]]s.<ref name=NCIBook2013 /> Diagnosis is typically made by [[blood test]]s or [[bone marrow biopsy]].<ref name=NCIBook2013 />

The exact cause of leukemia is unknown.<ref name=Hut2010/> A combination of [[heredity|genetic factors]] and environmental (non-inherited) factors are believed to play a role.<ref name=Hut2010>{{cite journal | vauthors = Hutter JJ | title = Childhood leukemia | journal = Pediatrics in Review | volume = 31 | issue = 6 | pages = 234–241 | date = June 2010 | pmid = 20516235 | doi = 10.1542/pir.31-6-234 | s2cid = 207170780 }}</ref> Risk factors include [[smoking]], [[ionizing radiation]], petrochemicals (such as [[benzene]]), prior chemotherapy, and [[Down syndrome]].<ref name=Hut2010 /><ref name=NCISnap /> People with a family history of leukemia are also at higher risk.<ref name=NCISnap /> There are four main types of leukemia—[[acute lymphoblastic leukemia]] (ALL), [[acute myeloid leukemia]] (AML), [[chronic lymphocytic leukemia]] (CLL) and [[chronic myeloid leukemia]] (CML)—and a number of less common types.<ref name=NCISnap>{{cite web|title=A Snapshot of Leukemia|url=http://www.cancer.gov/researchandfunding/snapshots/leukemia|website=NCI|access-date=18 June 2014|url-status=live|archive-url=https://web.archive.org/web/20140704183430/http://www.cancer.gov/researchandfunding/snapshots/leukemia|archive-date=4 July 2014}}</ref><ref name=WCR2014/> Leukemias and [[lymphoma]]s both belong to a broader group of [[tumor]]s that affect the blood, bone marrow, and [[lymphatic system|lymphoid system]], known as [[tumors of the hematopoietic and lymphoid tissues]].<ref>{{cite journal | vauthors = Vardiman JW, Thiele J, Arber DA, Brunning RD, Borowitz MJ, Porwit A, Harris NL, Le Beau MM, Hellström-Lindberg E, Tefferi A, Bloomfield CD | title = The 2008 revision of the World Health Organization (WHO) classification of myeloid neoplasms and acute leukemia: rationale and important changes | journal = Blood | volume = 114 | issue = 5 | pages = 937–951 | date = July 2009 | pmid = 19357394 | doi = 10.1182/blood-2009-03-209262 | s2cid = 3101472 | doi-access = free }}</ref><ref>{{cite book|veditors = Baba AI, Câtoi C |title=Comparative oncology|date=2007|publisher=The Publishing House of the Romanian Academy|location=Bucharest|isbn=978-973-27-1457-7|page=Chapter 17|url=https://www.ncbi.nlm.nih.gov/books/NBK9562/|url-status=live|archive-url=https://web.archive.org/web/20170910174530/https://www.ncbi.nlm.nih.gov/books/NBK9562/|archive-date=10 September 2017}}</ref>

Treatment may involve some combination of [[chemotherapy]], [[radiation therapy]], [[targeted therapy]], and [[bone marrow transplant]], with [[supportive care|supportive]] and [[palliative care]] provided as needed.<ref name=NCISnap/><ref name="BCDtargetedTherapy">{{cite journal | vauthors = Cordo' V, van der Zwet JC, Canté-Barrett K, Pieters R, Meijerink JP | title = T-cell Acute Lymphoblastic Leukemia: A Roadmap to Targeted Therapies | journal = Blood Cancer Discovery | volume = 2 | issue = 1 | pages = 19–31 | date = January 2021 | pmid = 34661151 | pmc = 8447273 | doi = 10.1158/2643-3230.BCD-20-0093 | doi-access = free }}</ref> Certain types of leukemia may be managed with [[watchful waiting]].<ref name=NCISnap/> The success of treatment depends on the type of leukemia and the age of the person. Outcomes have improved in the developed world.<ref name=WCR2014/> [[Five-year survival rate]] was 67% in the United States in the period from 2014 to 2020.<ref name=SEER>{{cite web| url = http://seer.cancer.gov/statfacts/html/leuks.html#incidence-mortality| title = SEER Stat Fact Sheets: Leukemia| year = 2024| publisher = National Cancer Institute| df = dmy-all}} Updated as required.</ref> In children under 15 in [[first-world]] countries, the five-year survival rate is greater than 60% or even 90%, depending on the type of leukemia. For infants (those diagnosed under the age of 1), the survival rate is around 40%.<ref name=ACS2014/> In children who are cancer-free five years after diagnosis of acute leukemia, the [[Cancer recurrence#Leukemia|cancer is unlikely to return]].<ref name=ACS2014>{{cite web|author1=American Cancer Society|title=Survival rates for childhood leukemia|url=http://www.cancer.org/cancer/leukemiainchildren/overviewguide/childhood-leukemia-overview-survival-rates|date=2 March 2014|url-status=live|archive-url=https://web.archive.org/web/20140714204805/http://www.cancer.org/cancer/leukemiainchildren/overviewguide/childhood-leukemia-overview-survival-rates|archive-date=14 July 2014}}</ref>

In 2015, leukemia was present in 2.3 million people worldwide and caused 353,500 deaths.<ref name=GBD2015Pre>{{cite journal | title = Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015 | journal = Lancet | volume = 388 | issue = 10053 | pages = 1545–1602 | date = October 2016 | pmid = 27733282 | pmc = 5055577 | doi = 10.1016/S0140-6736(16)31678-6 | last1 = Vos | first1 = Theo | last2 = Allen | first2 = Christine | last3 = Arora | first3 = Megha | last4 = Barber | first4 = Ryan M. | last5 = Bhutta | first5 = Zulfiqar A. | last6 = Brown | first6 = Alexandria | last7 = Carter | first7 = Austin | last8 = Casey | first8 = Daniel C. | last9 = Charlson | first9 = Fiona J. | last10 = Chen | first10 = Alan Z. | last11 = Coggeshall | first11 = Megan | last12 = Cornaby | first12 = Leslie | last13 = Dandona | first13 = Lalit | last14 = Dicker | first14 = Daniel J. | last15 = Dilegge | first15 = Tina | last16 = Erskine | first16 = Holly E. | last17 = Ferrari | first17 = Alize J. | last18 = Fitzmaurice | first18 = Christina | last19 = Fleming | first19 = Tom | last20 = Forouzanfar | first20 = Mohammad H. | last21 = Fullman | first21 = Nancy | last22 = Gething | first22 = Peter W. | last23 = Goldberg | first23 = Ellen M. | last24 = Graetz | first24 = Nicholas | last25 = Haagsma | first25 = Juanita A. | last26 = Hay | first26 = Simon I. | last27 = Johnson | first27 = Catherine O. | last28 = Kassebaum | first28 = Nicholas J. | last29 = Kawashima | first29 = Toana | last30 = Kemmer | first30 = Laura }}</ref><ref name=GBD2015De>{{cite journal | title = Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980–2015: a systematic analysis for the Global Burden of Disease Study 2015 | journal = Lancet | volume = 388 | issue = 10053 | pages = 1459–1544 | date = October 2016 | pmid = 27733281 | pmc = 5388903 | doi = 10.1016/s0140-6736(16)31012-1 | last1 = Wang | first1 = Haidong | last2 = Naghavi | first2 = Mohsen | last3 = Allen | first3 = Christine | last4 = Barber | first4 = Ryan M. | last5 = Bhutta | first5 = Zulfiqar A. | last6 = Carter | first6 = Austin | last7 = Casey | first7 = Daniel C. | last8 = Charlson | first8 = Fiona J. | last9 = Chen | first9 = Alan Zian | last10 = Coates | first10 = Matthew M. | last11 = Coggeshall | first11 = Megan | last12 = Dandona | first12 = Lalit | last13 = Dicker | first13 = Daniel J. | last14 = Erskine | first14 = Holly E. | last15 = Ferrari | first15 = Alize J. | last16 = Fitzmaurice | first16 = Christina | last17 = Foreman | first17 = Kyle | last18 = Forouzanfar | first18 = Mohammad H. | last19 = Fraser | first19 = Maya S. | last20 = Fullman | first20 = Nancy | last21 = Gething | first21 = Peter W. | last22 = Goldberg | first22 = Ellen M. | last23 = Graetz | first23 = Nicholas | last24 = Haagsma | first24 = Juanita A. | last25 = Hay | first25 = Simon I. | last26 = Huynh | first26 = Chantal | last27 = Johnson | first27 = Catherine O. | last28 = Kassebaum | first28 = Nicholas J. | last29 = Kinfu | first29 = Yohannes | last30 = Kulikoff | first30 = Xie Rachel }}</ref> In 2012, it had newly developed in 352,000 people.<ref name=WCR2014>{{cite book|title=World Cancer Report 2014 |date=2014|publisher=World Health Organization|isbn=978-92-832-0429-9 |pages=482–494 |chapter=5.13 Haematopoietic and lymphoid malignancies |chapter-url=https://archive.org/details/worldcancerrepor0000unse_p0u5/page/482/mode/2up}}</ref> It is the most common type of cancer in children, with three-quarters of leukemia cases in children being the acute lymphoblastic type.<ref name=NCISnap/> However, over 90% of all leukemias are diagnosed in adults, CLL and AML being most common.<ref name=NCISnap/><ref>{{Cite web|url=https://www.msdmanuals.com/en-pt/professional/hematology-and-oncology/leukemias/chronic-lymphocytic-leukemia-cll|title=Chronic Lymphocytic Leukemia (CLL) — Hematology and Oncology|website=MSD Manual Professional Edition|language=en-PT|access-date=2020-02-01}}</ref> It occurs more commonly in the [[developed world]].<ref name=WCR2014/>
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==Classification==
<!-- Incorrect use of [[WP:ITALICS]] throughout this section -->
{| class="wikitable" style="margin-left:15px; text-align:center"
|+Four major kinds of leukemia
! Cell type !! Acute !! Chronic
 |-
 | '''Lymphocytic leukemia'''<br />(or "lymphoblastic") || [[Acute lymphoblastic leukemia]]<br /> (ALL) || [[B-cell chronic lymphocytic leukemia|Chronic lymphocytic leukemia]]<br /> (CLL)
 |-
 | '''Myelogenous leukemia'''<br />("myeloid" or "nonlymphocytic") || [[Acute myeloid leukemia|Acute myelogenous leukemia]] <br />(AML or myeloblastic) || [[Chronic myelogenous leukemia]]<br /> (CML)
|}
[[File:Acute leukemia 1.webm|thumb|upright=1.4|An explanation of acute leukemia]]

===General classification===
Clinically and pathologically, leukemia is subdivided into a variety of large groups. The first division is between its ''[[Acute (medical)|acute]]'' and ''[[chronic (medicine)|chronic]]'' forms:<ref name=":1">{{Cite web |title=Questions and Answers About Leukemia |url=https://www.cdc.gov/nceh/radiation/phase2/mleukemi.pdf |url-status=live |archive-url=https://web.archive.org/web/20210730115224/https://www.cdc.gov/nceh/radiation/phase2/mleukemi.pdf |archive-date=July 30, 2021 |access-date=August 8, 2021 |website=[[Centers for Disease Control and Prevention]]}}</ref>
* [[Acute leukemia]] is characterized by a rapid increase in the number of immature blood cells. The crowding that results from such cells makes the bone marrow unable to produce healthy blood cells resulting in low [[hemoglobin]] and low [[platelet]]s. Immediate treatment is required in acute leukemia because of the rapid progression and accumulation of the [[malignant cell]]s, which then spill over into the bloodstream and spread to other organs of the body. Acute forms of leukemia are the most common forms of [[childhood leukemia|leukemia in children]].
* [[Chronic leukemia]] is characterized by the excessive buildup of relatively mature, but still abnormal, [[white blood cell]]s (or, more rarely, [[red blood cell]]s). Typically taking months or years to progress, the cells are produced at a much higher rate than normal, resulting in many abnormal white blood cells. Whereas acute leukemia must be treated immediately, chronic forms are sometimes monitored for some time before treatment to ensure maximum effectiveness of therapy. Chronic leukemia mostly occurs in older people but can occur in any age group.

Additionally, the diseases are subdivided according to which kind of blood cell is affected. This divides leukemias into [[Acute lymphoblastic leukemia|lymphoblastic]] or ''[[lymphocytic leukemia]]s'' and [[Myeloid leukemia|myeloid]] or ''[[myelogenous leukemia]]s'':<ref name=":1" />
* In lymphoblastic or [[lymphocytic leukemia]]s, the cancerous change takes place in a type of marrow cell that normally goes on to form [[lymphocyte]]s, which are infection-fighting immune system cells. Most lymphocytic leukemias involve a specific subtype of lymphocyte, the [[B&nbsp;cell]].
* In myeloid or [[myelogenous leukemia]]s, the cancerous change takes place in a [[myeloid cells|type of marrow cell]] that normally goes on to form [[red blood cell]]s, some other types of white cells, and [[platelet]]s.

Combining these two classifications provides a total of four main categories. Within each of these main categories, there are typically several subcategories. Finally, some rarer types are usually considered to be outside of this classification scheme.<ref name=":1" /><ref>{{Cite web|title=Leukemia — Symptoms and causes|url=https://www.mayoclinic.org/diseases-conditions/leukemia/symptoms-causes/syc-20374373|access-date=2021-08-08|website=Mayo Clinic|language=en}}</ref>

===Specific types===
* [[Acute lymphoblastic leukemia]] (ALL) is the most common type of leukemia in young children. It also affects adults, especially those 65 and older. Standard treatments involve [[chemotherapy]] and [[radiotherapy]]. Subtypes include [[precursor B acute lymphoblastic leukemia]], [[precursor T acute lymphoblastic leukemia]], [[Burkitt's leukemia]], and [[acute biphenotypic leukemia]]. While most cases of ALL occur in children, 80% of deaths from ALL occur in adults.<ref>{{cite web |url= https://www.cancer.org/cancer/acute-lymphocytic-leukemia/about/key-statistics.html/|title= Key Statistics for Acute Lymphocytic Leukemia (ALL)|date=8 January 2019 |website=American Cancer Society |access-date=9 December 2019}}</ref>
*  [[Chronic lymphocytic leukemia]] (CLL) most often affects adults over the age of 55. It sometimes occurs in younger adults, but it almost never affects children. Two-thirds of affected people are men. The five-year survival rate is 85%.<ref>{{cite web | url = http://seer.cancer.gov/statfacts/html/clyl.html | title = Finding Cancer Statistics » Cancer Stat Fact Sheets »Chronic Lymphocytic Leukemia | archive-url = https://web.archive.org/web/20080416053309/http://seer.cancer.gov/statfacts/html/clyl.html| archive-date=16 April 2008 | work = National Cancer Institute }}</ref> It is incurable, but there are many effective treatments. One subtype is [[B-cell prolymphocytic leukemia]], a more aggressive disease.
* [[Acute myelogenous leukemia]] (AML) occurs far more commonly in adults than in children, and more commonly in men than women. It is treated with chemotherapy. The five-year survival rate is 20%.<ref>{{cite web |url=https://www.cancerresearchuk.org/about-cancer/acute-myeloid-leukaemia-aml/survival/|title=Survival: Acute Myeloid Leukaemia |date=10 July 2019 |website=Cancer Research UK |access-date=2 December 2019}}</ref> Subtypes of AML include [[acute promyelocytic leukemia]], [[acute myeloblastic leukemia]], and [[acute megakaryoblastic leukemia]].
* [[Chronic myelogenous leukemia]] (CML) occurs mainly in adults; a very small number of children also develop this disease. It is treated with [[imatinib]] (Gleevec in United States, Glivec in Europe) or other drugs.<ref>{{cite web|url=http://www.novartisoncology.com|title=Novartis Oncology|url-status=live|archive-url=https://web.archive.org/web/20131105145436/http://www.novartisoncology.com/|archive-date=5 November 2013}}</ref> The five-year survival rate is 90%.<ref>{{cite web | vauthors = Moyer P | date = 12 June 2006 | url = http://www.medscape.com/viewarticle/536049 | title = Patients with Chronic Myelogenous Leukemia Continue to Do Well on Imatinib at 5-Year Follow-Up | archive-url = https://web.archive.org/web/20130515063623/http://www.medscape.com/viewarticle/536049 | archive-date = 15 May 2013 | work = Medscape Medical News }}</ref><ref>{{cite web | url = http://professional.cancerconsultants.com/conference_asco_2006.aspx?id=37519 | title = Updated Results of Tyrosine Kinase Inhibitors in CML | archive-url = https://web.archive.org/web/20071229125528/http://professional.cancerconsultants.com/conference_asco_2006.aspx?id=37519 | archive-date=29 December 2007 | work = ASCO 2006 Conference Summaries }}</ref> One subtype is [[chronic myelomonocytic leukemia]].
* [[Hairy cell leukemia]] (HCL) is sometimes considered a subset of chronic lymphocytic leukemia, but does not fit neatly into this category. About 80% of affected people are adult men. No cases in children have been reported. HCL is incurable but easily treatable. Survival is 96% to 100% at ten years.<ref name="pmid16245328">{{cite journal | vauthors = Else M, Ruchlemer R, Osuji N, Del Giudice I, Matutes E, Woodman A, Wotherspoon A, Swansbury J, Dearden C, Catovsky D | title = Long remissions in hairy cell leukemia with purine analogs: a report of 219 patients with a median follow-up of 12.5 years | journal = Cancer | volume = 104 | issue = 11 | pages = 2442–8 | date = December 2005 | pmid = 16245328 | doi = 10.1002/cncr.21447 | s2cid = 43282431 | doi-access = free }}</ref>
* [[T-cell prolymphocytic leukemia]] (T-PLL) is a very rare and aggressive leukemia affecting adults; somewhat more men than women are diagnosed with this disease.<ref>{{cite journal | vauthors = Matutes E | title = T-cell Prolymphocytic Leukemia | journal = Cancer Control | volume = 5 | issue = 1 | pages = 19–24 | date = January 1998 | pmid = 10761013 | doi = 10.1177/107327489800500102 | url = http://www.moffitt.org/moffittapps/ccj/v5n1/article2.html | url-status = live | doi-access = free | archive-url = https://web.archive.org/web/20090211044933/http://www.moffitt.org/moffittapps/ccj/v5n1/article2.html | archive-date = 11 February 2009 | url-access = subscription }}</ref> Despite its overall rarity, it is the most common type of mature [[T cell]] leukemia;<ref name="pmid15716243">{{cite journal | vauthors = Valbuena JR, Herling M, Admirand JH, Padula A, Jones D, Medeiros LJ | title = T-cell prolymphocytic leukemia involving extramedullary sites | journal = American Journal of Clinical Pathology | volume = 123 | issue = 3 | pages = 456–464 | date = March 2005 | pmid = 15716243 | doi = 10.1309/93P4-2RNG-5XBG-3KBE | url = http://www.medscape.com/viewarticle/501092 | url-status = live | doi-access = free | archive-url = https://web.archive.org/web/20130515093513/http://www.medscape.com/viewarticle/501092 | archive-date = 15 May 2013 }}</ref> nearly all other leukemias involve [[B cells]]. It is difficult to treat, and the median survival is measured in months.
* [[Large granular lymphocytic leukemia]] may involve either T-cells or [[NK cell]]s; like hairy cell leukemia, which involves solely B cells, it is a rare and [[Indolent condition|indolent]] (not aggressive) leukemia.<ref name="who1">{{cite book | vauthors = Jaffe ES, Harris NL, Stein H, Vardiman JW | collaboration = World Health Organization, International Agency for Research on Cancer |title=Pathology and genetics of tumours of haematopoietic and lymphoid tissues |publisher=IARC Press |location=Lyon |year=2001 |series=World Health Organization Classification of Tumors |volume=3 |isbn=978-92-832-2411-2 |url=https://books.google.com/books?id=XSKqcy7TUZUC}}</ref>
* [[Adult T-cell leukemia/lymphoma|Adult T-cell leukemia]] is caused by [[human T-lymphotropic virus]] (HTLV), a virus similar to [[human immunodeficiency virus|HIV]]. Like HIV, HTLV infects CD4+ T-cells and replicates within them; however, unlike HIV, it does not destroy them. Instead, HTLV "immortalizes" the infected T-cells, giving them the ability to proliferate abnormally. Human T-cell lymphotropic virus types I and II (HTLV-I/II) are endemic in certain areas of the world.{{citation needed|date=March 2021}}
* [[Clonal eosinophilia]]s (also called ''clonal hypereosinophilias'') are a group of blood disorders characterized by the growth of [[eosinophil]]s in the [[bone marrow]], blood, and/or other tissues.   They may be [[pre-malignant|pre-cancerous]] or [[malignant|cancerous]]. Clonal eosinophilias involve a [[Clone (cell biology)|"clone"]] of eosinophils, i.e., a group of genetically identical eosinophils that all grew from the same [[mutated]] ancestor cell.<ref name="pmid28028030">{{cite journal | vauthors = Reiter A, Gotlib J | title = Myeloid neoplasms with eosinophilia | journal = Blood | volume = 129 | issue = 6 | pages = 704–714 | date = February 2017 | pmid = 28028030 | doi = 10.1182/blood-2016-10-695973 | doi-access = free }}</ref> These disorders may evolve into [[chronic eosinophilic leukemia]] or may be associated with various forms of [[myeloid]] neoplasms, [[lymphoid]] neoplasms, [[myelofibrosis]], or the [[myelodysplastic syndrome]].<ref name="pmid26486351">{{cite journal | vauthors = Gotlib J | title = World Health Organization-defined eosinophilic disorders: 2015 update on diagnosis, risk stratification, and management | journal = American Journal of Hematology | volume = 90 | issue = 11 | pages = 1077–89 | date = November 2015 | pmid = 26486351 | doi = 10.1002/ajh.24196 | s2cid = 42668440 | doi-access = free }}</ref><ref name="pmid27069254">{{cite journal | vauthors = Arber DA, Orazi A, Hasserjian R, Thiele J, Borowitz MJ, Le Beau MM, Bloomfield CD, Cazzola M, Vardiman JW | title = The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia | journal = Blood | volume = 127 | issue = 20 | pages = 2391–2405 | date = May 2016 | pmid = 27069254 | doi = 10.1182/blood-2016-03-643544 | s2cid = 18338178 | doi-access = free }}</ref><ref name="pmid28028030"/>

===Pre-leukemia===
* [[Transient myeloproliferative disease]], also termed transient leukemia, involves the abnormal proliferation of a [[Clone (cell biology)|clone]] of non-cancerous [[megakaryoblast]]s. The disease is restricted to individuals with [[Down syndrome]] or genetic changes similar to those in Down syndrome, develops in a baby during pregnancy or shortly after birth, and resolves within 3 months or, in ~10% of cases, progresses to [[acute megakaryoblastic leukemia]]. Transient myeloid leukemia is a pre-leukemic condition.<ref name="pmid27510823">{{cite journal | vauthors = Bhatnagar N, Nizery L, Tunstall O, Vyas P, Roberts I | title = Transient Abnormal Myelopoiesis and AML in Down Syndrome: an Update | journal = Current Hematologic Malignancy Reports | volume = 11 | issue = 5 | pages = 333–341 | date = October 2016 | pmid = 27510823 | pmc = 5031718 | doi = 10.1007/s11899-016-0338-x }}</ref><ref name="pmid28179280">{{cite journal | vauthors = Crispino JD, Horwitz MS | title = GATA factor mutations in hematologic disease | journal = Blood | volume = 129 | issue = 15 | pages = 2103–10 | date = April 2017 | pmid = 28179280 | pmc = 5391620 | doi = 10.1182/blood-2016-09-687889 }}</ref><ref name="pmid22867885">{{cite journal | vauthors = Seewald L, Taub JW, Maloney KW, McCabe ER | title = Acute leukemias in children with Down syndrome | journal = Molecular Genetics and Metabolism | volume = 107 | issue = 1–2 | pages = 25–30 | date = September 2012 | pmid = 22867885 | doi = 10.1016/j.ymgme.2012.07.011 }}</ref>
* [[Clonal hematopoiesis]] is a common age-related phenomenon with a low risk of progression to [[myelodysplastic syndrome]] (MDS) and leukemia.<ref>{{cite journal |vauthors=Weeks LD, Ebert BL |title=Causes and consequences of clonal hematopoiesis |journal=Blood |volume=142 |issue=26 |pages=2235–46 |date=December 2023 |pmid=37931207 |doi=10.1182/blood.2023022222 |doi-access=free |pmc=10862247 }}</ref> Once MDS has developed, the risk of progression to acute leukemia can be assessed using the International Prognostic Scoring System ([[International Prognostic Scoring System|IPSS]]).
* [[Monoclonal B-cell lymphocytosis]] has a low risk of progression to B-cell leukemia.

==Signs and symptoms==
[[File:Symptoms of leukemia.png|thumb|upright=1.4|Common symptoms of chronic or acute leukemia<ref>Reference list is found at [[Commons:File:Symptoms of leukemia.png#List|image description page in Wikimedia Commons]]</ref>]]

The most common symptoms in children are easy [[bruising]], [[pale skin]], [[fever]], and an [[enlarged spleen]] or [[hepatomegaly|liver]].<ref>{{cite journal | vauthors = Clarke RT, Van den Bruel A, Bankhead C, Mitchell CD, Phillips B, Thompson MJ | title = Clinical presentation of childhood leukaemia: a systematic review and meta-analysis | journal = Archives of Disease in Childhood | volume = 101 | issue = 10 | pages = 894–901 | date = October 2016 | pmid = 27647842 | doi = 10.1136/archdischild-2016-311251 | doi-access = free }}</ref>

Damage to the bone marrow, by way of displacing the normal bone marrow cells with higher numbers of immature white blood cells, results in a lack of blood [[platelet]]s, which are important in the [[Coagulation of human blood|blood clotting]] process. This means people with leukemia may easily become [[purpura|bruised]], [[hemorrhage|bleed]] excessively, or develop pinprick bleeds ([[petechia]]e).<ref>{{cite journal | vauthors = Jyothi KT, Subrahmanyam PS, Sravanthi AC |date=July 2017 |title=Application of Differential Equations in Medical Science |journal=Research Journal of Science and Technology |volume=9 |issue=3 |pages=425–6 |doi=10.5958/2349-2988.2017.00074.2 |doi-access=free }}</ref>

[[White blood cell]]s, which are involved in fighting [[pathogen]]s, may be suppressed or dysfunctional. This could cause the person's immune system to be unable to fight off a simple infection or to start attacking other body cells. Because leukemia prevents the immune system from working normally, some people experience frequent [[infection]], ranging from infected [[tonsil]]s, [[oral ulcer|sores in the mouth]], or [[diarrhea]] to life-threatening [[pneumonia]] or [[opportunistic infection]]s.<ref>{{Cite web|date=2018-10-05|title=Types of Leukemia: Common, Rare and More Varieties|url=https://www.cancercenter.com/cancer-types/leukemia/types|access-date=2021-10-08|website=Cancer Treatment Centers of America|language=en}}</ref>

Finally, the red blood cell deficiency leads to [[anemia]], which may cause [[dyspnea]] and [[pallor]].<ref>{{Cite web |title=Iron deficiency anemia — Symptoms and causes |url=https://www.mayoclinic.org/diseases-conditions/iron-deficiency-anemia/symptoms-causes/syc-20355034 |access-date=2022-03-05 |website=Mayo Clinic |language=en}}</ref>

Some people experience other symptoms, such as fevers, chills, night sweats, weakness in the limbs, feeling [[fatigue (medical)|fatigued]] and other common [[flu-like symptoms]]. Some people experience nausea or a feeling of fullness due to an enlarged [[liver]] and [[spleen]]; this can result in unintentional [[Weight loss#Intentional weight loss|weight loss]]. [[Precursor cell|Blasts]] affected by the disease may come together and become swollen in the liver or in the [[lymph nodes]] causing pain and leading to nausea.<ref>{{cite web|title=Leukemia|url=http://connection.ebscohost.com/c/articles/39018085|publisher=Columbia Electronic Encyclopedia, 6th Edition|access-date=4 November 2011}}</ref>

If the leukemic cells invade the [[central nervous system]], then neurological symptoms (notably [[headache]]s) can occur. Uncommon neurological symptoms like [[migraines]], [[seizures]], or [[coma]] can occur as a result of brain stem pressure. All symptoms associated with leukemia can be attributed to other diseases. Consequently, leukemia is always diagnosed through [[medical test]]s.

The word ''leukemia'', which means 'white blood', is derived from the characteristic high white blood cell count that presents in most affected people before treatment. The high number of white blood cells is apparent when a blood sample is [[Blood film|viewed under a microscope]], with the extra white blood cells frequently being immature or dysfunctional. The excessive number of cells can also interfere with the level of other cells, causing further harmful imbalance in the blood count.<ref>{{Cite web |title=Leukemia: Symptoms, Signs, Causes, Types & Treatment |url=https://my.clevelandclinic.org/health/diseases/4365-leukemia |access-date=2022-10-13 |website=Cleveland Clinic}}</ref>

Some people diagnosed with leukemia do not have high white blood cell counts visible during a regular blood count. This less-common condition is called ''aleukemia''. The bone marrow still contains cancerous white blood cells that disrupt the normal production of blood cells, but they remain in the marrow instead of entering the bloodstream, where they would be visible in a blood test. For a person with aleukemia, the white blood cell counts in the bloodstream can be normal or low. Aleukemia can occur in any of the four major types of leukemia, and is particularly common in [[hairy cell leukemia]].<ref name=ACS1/>

==Causes==

Studies in 2009 and 2010 have shown a positive correlation between exposure to [[formaldehyde]] and the development of leukemia, particularly [[myeloid leukemia]].<ref>{{cite journal
| last1=Zhang
| first1=Luoping
| last2=Steinmaus
| first2=Craig
| last3=Eastmond
| first3=Eastmond
| last4=Xin
| first4=Xin
| last5=Smith
| first5=Smith
| title=Formaldehyde exposure and leukemia: A new meta-analysis and potential mechanisms
| url=http://ehs.sph.berkeley.edu/krsmith/CRA/cancer/ZhangL_2008.pdf
| date=March–June 2009
| volume=681
| pages=150–168
| pmid=18674636
| doi=10.1016/j.mrrev.2008.07.002
| access-date=2013-05-22
| journal=Mutation Research/Reviews in Mutation Research
| issue=2–3
| archive-url=https://web.archive.org/web/20140327073359/http://ehs.sph.berkeley.edu/krsmith/CRA/cancer/ZhangL_2008.pdf
| archive-date=2014-03-27
| url-status=dead
}}</ref><ref>{{cite journal
| doi=10.1002/em.20534
| pmid=19790261
| title=Formaldehyde and Leukemia: Epidemiology, Potential Mechanisms, and Implications for Risk Assessment
| year=2010
| volume=51
| issue=3
| pages=181–191
| journal=Environmental and Molecular Mutagenesis| pmc=2839060
| last1=Zhang
| first1=Luoping
| last2=Freeman
| first2=Laura E. Beane
| last3=Nakamura
| first3=Jun
| last4=Hecht
| first4=Stephen S.
| last5=Vandenberg
| first5=John J.
| last6=Smith
| first6=Martyn T.
| last7=Sonawane
| first7=Babasaheb R.
| bibcode=2010EnvMM..51..181Z
}}</ref> The different leukemias likely have different causes.<ref>{{cite book | veditors = Novak EM, Rego EM | title = Physiopathogenesis of Hematological Cancer | publisher = Bentham Science Publishers | date = 2012 | isbn = 978-1-60805-259-2 }}</ref>

Leukemia, like other cancers, results from [[somatic mutation|mutations]] in the [[DNA]]. Certain mutations can trigger leukemia by activating [[oncogene]]s or deactivating [[tumor suppressor gene]]s, and thereby disrupting the regulation of cell death, differentiation or division. These mutations may occur spontaneously or as a result of exposure to [[ionizing radiation|radiation]] or [[carcinogen]]ic substances.<ref>{{cite journal | vauthors = Radivoyevitch T, Sachs RK, Gale RP, Molenaar RJ, Brenner DJ, Hill BT, Kalaycio ME, Carraway HE, Mukherjee S, Sekeres MA, Maciejewski JP | title = Defining AML and MDS second cancer risk dynamics after diagnoses of first cancers treated or not with radiation | journal = Leukemia | volume = 30 | issue = 2 | pages = 285–294 | date = February 2016 | pmid = 26460209 | doi = 10.1038/leu.2015.258 | s2cid = 22100511 }}</ref>

Among adults, the known causes are natural and artificial [[ionizing radiation]] and petrochemicals, notably [[benzene]] and alkylating [[chemotherapy]] agents for previous malignancies.<ref name="isbn1-55009-111-5">{{cite book| vauthors = Wiernik PH |title=Adult leukemias|publisher=B. C. Decker|location=New York|year=2001|pages=3–15|isbn=978-1-55009-111-3}}</ref><ref name="isbn1-893441-36-9">{{cite book | vauthors = Robinette MS, Cotter S, Van de Water D |title=Quick Look Series in Veterinary Medicine: Hematology|publisher=Teton NewMedia|year=2001|page=105|isbn=978-1-893441-36-1}}</ref><ref name="isbn0-8247-0170-4">{{cite book| vauthors = Stass SA, Schumacher HR, Rock WR |title=Handbook of hematologic pathology|url=https://archive.org/details/handbookhematolo00schu |url-access=limited |publisher=Marcel Dekker|location=New York, N.Y|year=2000|pages=[https://archive.org/details/handbookhematolo00schu/page/n208 193]–194|isbn=978-0-8247-0170-3}}</ref> Use of [[tobacco]] is associated with a small increase in the risk of developing [[acute myeloid leukemia]] in adults.<ref name="isbn1-55009-111-5" /> Cohort and case-control studies have linked exposure to some [[petrochemicals]] and [[hair dye]]s to the development of some forms of leukemia. Diet has very limited or no effect, although eating more vegetables may confer a small protective benefit.<ref name="pmid12163333">{{cite journal | vauthors = Ross JA, Kasum CM, Davies SM, Jacobs DR, Folsom AR, Potter JD | title = Diet and risk of leukemia in the Iowa Women's Health Study | journal = Cancer Epidemiology, Biomarkers & Prevention | volume = 11 | issue = 8 | pages = 777–781 | date = August 2002 | pmid = 12163333 | url = http://cebp.aacrjournals.org/content/11/8/777.long | url-status = live | archive-url = https://web.archive.org/web/20170910174529/http://cebp.aacrjournals.org/content/11/8/777.long | archive-date = 10 September 2017 }}</ref>

Viruses have also been linked to some forms of leukemia.  For example, [[human T-lymphotropic virus]] (HTLV-1) causes [[adult T-cell leukemia]].<ref>{{cite book| vauthors = Leonard B |title=Leukemia: A Research Report|year=1998|publisher=DIANE Publishing|isbn=978-0-7881-7189-5|page=[https://books.google.com/books?id=VfFCVvX9btYC&pg=PA7 7]|url=https://books.google.com/books?id=VfFCVvX9btYC&q=leukemia}}</ref>

A few cases of [[maternal-fetal transmission]] (a baby acquires leukemia because its mother had leukemia during the pregnancy) have been reported.<ref name="isbn1-55009-111-5" /> Children born to mothers who use [[fertility medication|fertility drugs]] to induce ovulation are more than twice as likely to develop leukemia during their childhoods than other children.<ref name="Rudant2012">{{cite journal | vauthors = Rudant J, Amigou A, Orsi L, Althaus T, Leverger G, Baruchel A, Bertrand Y, Nelken B, Plat G, Michel G, Sirvent N, Chastagner P, Ducassou S, Rialland X, Hémon D, Clavel J | title = Fertility treatments, congenital malformations, fetal loss, and childhood acute leukemia: the ESCALE study (SFCE) | journal = Pediatric Blood & Cancer | volume = 60 | issue = 2 | pages = 301–8 | date = February 2013 | pmid = 22610722 | doi = 10.1002/pbc.24192 | s2cid = 26010916 }}</ref>

In a recent systematic review and meta-analysis of any type of leukemia in neonates using [[Light therapy|phototherapy]], typically to treat [[neonatal jaundice]], a statistically significant association was detected between using phototherapy and myeloid leukemia. However, it is still questionable whether phototherapy is genuinely the cause of cancer or simply a result of the same underlying factors that gave rise to cancer.<ref>{{cite journal |vauthors=Abdellatif M, Tawfik GM, Makram AM, Abdelsattar MK, Dobs M, Papadopoulos DN, Hoang-Trong BL, Mostafa EM, Duong PD, Huy NT |title=Association between neonatal phototherapy and future cancer: an updated systematic review and meta-analysis |journal=Eur J Pediatr |volume=182 |issue=1 |pages=329–341 |date=January 2023 |pmid=36352244 |doi=10.1007/s00431-022-04675-6 }}</ref>

===Radiation===
Large doses of [[Strontium-90|Sr-90]] (called a [[bone seeker|bone seeking]] radioisotope) from [[nuclear reactor]] accidents, increases the risk of [[Osteosarcoma|bone cancer]] and leukemia in animals and is presumed to do so in people.<ref>{{cite web |title=Backgrounder on Radiation Protection and the "Tooth Fairy" Issue |url = https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/tooth-fairy.html | archive-url = https://web.archive.org/web/20170720060330/https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/tooth-fairy.html | archive-date = 20 July 2017 | publisher = U.S. Nuclear Regulatory Commission | date = December 2004 }}</ref>

===Genetic conditions===
Some people have a genetic predisposition towards developing leukemia. This predisposition is demonstrated by family histories and [[Twin study|twin studies]].<ref name="isbn1-55009-111-5" /> The affected people may have a single gene or multiple genes in common. In some cases, families tend to develop the same kinds of leukemia as other members; in other families, affected people may develop different forms of [[hematological malignancies|leukemia or related blood cancers]].<ref name="isbn1-55009-111-5" />

In addition to these genetic issues, people with chromosomal abnormalities or certain other genetic conditions have a greater risk of leukemia.<ref name="isbn1-893441-36-9" /> For example, people with [[Down syndrome]] have a significantly increased risk of developing forms of acute leukemia (especially [[acute myeloid leukemia]]), and [[Fanconi anemia]] is a risk factor for developing acute myeloid leukemia.<ref name="isbn1-55009-111-5" /> Mutation in [[SPRED1 gene]] has been associated with a predisposition to childhood leukemia.<ref>{{cite journal | vauthors = Pasmant E, Ballerini P, Lapillonne H, Perot C, Vidaud D, Leverger G, Landman-Parker J | title = SPRED1 disorder and predisposition to leukemia in children | journal = Blood | volume = 114 | issue = 5 | pages = 1131 | date = July 2009 | pmid = 19643996 | doi = 10.1182/blood-2009-04-218503 | doi-access = free }}</ref>

Inherited [[bone marrow failure]] syndromes represent a kind of premature aging of the bone marrow. In people with these syndromes and in older adults, mutations associated with [[clonal hematopoiesis]] may arise as an adaptive response to a progressively deteriorating hematopoietic niche, i.e., a depleting pool of [[Hematopoietic stem cells]]. The mutated stem cells then acquire a self-renewal advantage.<ref>{{cite journal |vauthors=Hall T, Gurbuxani S, Crispino JD |title=Malignant progression of preleukemic disorders |journal=Blood |volume=143 |issue=22 |pages=2245–55 |date=May 2024 |pmid=38498034 |doi=10.1182/blood.2023020817 |pmc=11181356 }}</ref>

[[Chronic myelogenous leukemia]] is associated with a genetic abnormality called the [[Philadelphia chromosome|Philadelphia translocation]]; 95% of people with CML carry the Philadelphia mutation, although this is not exclusive to CML and can be observed in people with other types of leukemia.<ref>{{cite journal | vauthors = Salesse S, Verfaillie CM | title = BCR/ABL: from molecular mechanisms of leukemia induction to treatment of chronic myelogenous leukemia | journal = Oncogene | volume = 21 | issue = 56 | pages = 8547–59 | date = December 2002 | pmid = 12476301 | doi = 10.1038/sj.onc.1206082 | doi-access = free }}</ref><ref>{{Cite web|url=https://www.cancer.gov/publications/dictionaries/cancer-terms?cdrid=44179|title=NCI Dictionary of Cancer Terms|website=National Cancer Institute|language=en|access-date=15 February 2017|url-status=live|archive-url=https://web.archive.org/web/20170216141643/https://www.cancer.gov/publications/dictionaries/cancer-terms?cdrid=44179|archive-date=16 February 2017|date=2 February 2011}}</ref><ref>{{Cite web|url=https://www.cancer.org/cancer/chronic-myeloid-leukemia/causes-risks-prevention/what-causes.html|title=Do We Know What Causes Chronic Myeloid Leukemia?|website=www.cancer.org|access-date=15 February 2017|url-status=live|archive-url=https://web.archive.org/web/20170216144606/https://www.cancer.org/cancer/chronic-myeloid-leukemia/causes-risks-prevention/what-causes.html|archive-date=16 February 2017}}</ref><ref>{{Cite web|url=http://www.macmillan.org.uk/information-and-support/leukaemia/leukaemia-chronic-myeloid/understanding-cancer/what-is-leukaemia.html|title=What is chronic myeloid leukaemia? (CML) — Understanding — Macmillan Cancer Support|website=www.macmillan.org.uk|language=en|access-date=15 February 2017|url-status=live|archive-url=https://web.archive.org/web/20170216133037/http://www.macmillan.org.uk/information-and-support/leukaemia/leukaemia-chronic-myeloid/understanding-cancer/what-is-leukaemia.html|archive-date=16 February 2017}}</ref>

===Non-ionizing radiation===
Whether or not non-ionizing radiation causes leukemia has been studied for several decades. The [[International Agency for Research on Cancer]] expert working group undertook a detailed review of all data on static and [[extremely low frequency]] electromagnetic energy, which occurs naturally and in association with the generation, transmission, and use of electrical power.<ref name="isbn92-832-1280-0">{{cite book|title=Non-Ionizing Radiation, Part 1: Static and Extremely Low-Frequency (ELF) Electric and Magnetic Fields (IARC Monographs on the Evaluation of the Carcinogenic Risks)|publisher=World Health Organisation|location=Geneva|year=2002|pages=332–3, 338|isbn=978-92-832-1280-5|url=http://monographs.iarc.fr/ENG/Monographs/vol80/index.php|url-status=live|archive-url=https://web.archive.org/web/20081206231737/http://monographs.iarc.fr/ENG/Monographs/vol80/index.php|archive-date=6 December 2008}}</ref> They concluded that there is limited evidence that high levels of [[Extremely low frequency|ELF]] magnetic (but not electric) fields might cause some cases of [[childhood leukemia]].<ref name="isbn92-832-1280-0" /> No evidence for a relationship to leukemia or another form of malignancy in adults has been demonstrated.<ref name="isbn92-832-1280-0" /> Since exposure to such levels of ELFs is relatively uncommon, the [[World Health Organization]] concludes that ELF exposure, if later proven to be causative, would account for just 100 to 2400 cases worldwide each year, representing 0.2 to 4.9% of the total incidence of childhood leukemia for that year (about 0.03 to 0.9% of all leukemias).<ref name="urlWHO | Electromagnetic fields and public health">{{cite web|url=https://www.who.int/mediacentre/factsheets/fs322/en/index.html|title=WHO &#124; Electromagnetic fields and public health|access-date=18 February 2009|url-status=dead|archive-url=https://web.archive.org/web/20090216160809/http://www.who.int/mediacentre/factsheets/fs322/en/index.html|archive-date=16 February 2009}}</ref>

==Diagnosis==
[[File:Leukemia- SAG.jpg|thumb|upright=1.3|The increase in [[white blood cell]]s in leukemia]]
Diagnosis is usually based on repeated [[complete blood count]]s and a [[bone marrow examination]] following observations of the symptoms.  Sometimes, blood tests may not show that a person has leukemia, especially in the early stages of the disease or during remission.  A [[lymph node biopsy]] can be performed to diagnose certain types of leukemia in certain situations.<ref>{{Cite web |title=Diagnosing Chronic Lymphocytic Leukemia in Adults |url=https://nyulangone.org/conditions/chronic-lymphocytic-leukemia-in-adults/diagnosis |url-status=live |archive-url=https://archive.today/20210326200439/https://nyulangone.org/conditions/chronic-lymphocytic-leukemia-in-adults/diagnosis |archive-date=2021-03-26 |access-date=2021-03-26 |website=NYU Langone Health}}</ref>

Following diagnosis, blood chemistry tests can be used to determine the degree of liver and kidney damage or the effects of chemotherapy on the person. When concerns arise about other damages due to leukemia, doctors may use an [[Radiography|X-ray]], [[MRI]], or [[Medical ultrasonography|ultrasound]].  These can potentially show leukemia's effects on such body parts as bones (X-ray), the brain (MRI), or the kidneys, spleen, and liver (ultrasound).  [[CT scans]] can be used to check lymph nodes in the chest, though this is uncommon.<ref>{{Cite web |title=Chronic Lymphocytic Leukemia (CLL): Tests After Diagnosis |url=https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=34&contentid=BCLL04 |url-status=live |archive-url=https://archive.today/20210326200920/https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=34&contentid=BCLL04 |archive-date=2021-03-26 |access-date=2021-03-26 |website=University of Rochester Medical Center }}</ref>

Despite the use of these methods to diagnose whether or not a person has leukemia, many people have not been diagnosed because many of the symptoms are vague, [[Non-specific symptom|non-specific]], and can refer to other diseases.  For this reason, the American Cancer Society estimates that at least one-fifth of the people with leukemia have not yet been diagnosed.<ref name=ACS1>{{cite web|url=http://www.cancer.org/docroot/cri/content/cri_2_4_3x_how_is_leukemia_diagnosed_62.asp |title=How is Leukemia Diagnosed? |author=American Cancer Society |year=2010 |work=Detailed Guide: Leukemia — Adult Chronic |publisher=American Cancer Society |access-date=4 May 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100405215530/http://www.cancer.org/docroot/cri/content/cri_2_4_3x_how_is_leukemia_diagnosed_62.asp |archive-date=5 April 2010 }}</ref>

==Treatment==
Most forms of leukemia are treated with pharmaceutical [[medication]], typically combined into a multi-drug [[chemotherapy regimen]]. Some are also treated with [[radiation therapy]]. In some cases, a [[bone marrow transplant]] is effective.

===Acute lymphoblastic===
{{Further|Acute lymphoblastic leukemia#Treatment}}
Management of ALL is directed towards control of bone marrow and systemic (whole-body) disease. Additionally, treatment must prevent leukemic cells from spreading to other sites, particularly the [[central nervous system]] (CNS); periodic lumbar punctures are used for diagnostic purposes and to administer intrathecal prophylactic methotrexate.<ref>{{cite journal |vauthors=Gaietto A, Panetta JC, Pauley JL, Relling MV, Ribeiro R, Ehrhardt MJ, Pui CH, Inaba H, Swanson HD |title=Ommaya reservoir use in pediatric ALL and NHL: a review at St. Jude Children's Research Hospital |journal=Cancer Chemother Pharmacol |volume=93 |issue=6 |pages=617–625 |date=June 2024 |pmid=38416167 |doi=10.1007/s00280-024-04653-9 |pmc=11376002 }}</ref> In general, ALL treatment is divided into several phases:
* ''Induction chemotherapy'' to bring about bone marrow remission. For adults, standard induction plans include [[prednisone]], [[vincristine]], and an [[anthracycline]] drug; other drug plans may include [[L-asparaginase]] or [[cyclophosphamide]]. For children with low-risk ALL, standard therapy usually consists of three drugs (prednisone, L-asparaginase, and vincristine) for the first month of treatment.
* ''Consolidation therapy'' or ''intensification therapy'' to eliminate any remaining leukemia cells. There are many different approaches to consolidation, but it is typically a high-dose, multi-drug treatment that is undertaken for a few months. People with low- to average-risk ALL receive therapy with [[antimetabolite]] drugs such as [[methotrexate]] and [[6-mercaptopurine]] (6-MP). People who are high-risk receive higher drug doses of these drugs, plus additional drugs.
* ''[[Central nervous system prophylaxis|CNS prophylaxis]]'' (preventive therapy) to stop cancer from spreading to the brain and nervous system in high-risk people. Standard [[prophylaxis]] may include radiation of the head and/or drugs delivered directly into the spine.
* ''Maintenance treatments'' with chemotherapeutic drugs to prevent disease recurrence once remission has been achieved. Maintenance therapy usually involves lower drug doses and may continue for up to three years.
* Alternatively, ''[[allogeneic bone marrow transplantation]]'' may be appropriate for high-risk or relapsed people.<ref>{{cite book| vauthors = Hoffbrand AV, Moss PA, Pettit JE |title=Essential haematology|date=2006|publisher=Blackwell Pub. |location=Malden, Mass. |isbn=978-1-4051-3649-5 |edition=5th}}</ref>

===Chronic lymphocytic===
{{Further|Chronic lymphocytic leukemia#Treatment}}

====Decision to treat====
[[Hematologist]]s base CLL treatment on both the stage and symptoms of the individual person. A large group of people with CLL have low-grade disease, which does not benefit from treatment. Individuals with CLL-related complications or more advanced disease often benefit from treatment. In general, the indications for treatment are:
* Falling [[hemoglobin]] or [[platelet]] count
* Progression to a later stage of disease
* Painful, disease-related overgrowth of [[lymph node]]s or [[spleen]]
* An increase in the rate of [[lymphocyte]] production<ref>{{cite web |url=http://www.cancer.gov/cancertopics/pdq/treatment/CLL/HealthProfessional/page2 |title=Chronic Lymphocytic Leukemia (PDQ) Treatment: Stage Information |author=National Cancer Institute |access-date=4 September 2007 |url-status=live |archive-url=https://web.archive.org/web/20071017143320/http://www.cancer.gov/cancertopics/pdq/treatment/CLL/HealthProfessional/page2 |archive-date=17 October 2007  |date=1 January 1980 }}</ref>

====Treatment approach====
Most CLL cases are incurable by present treatments, so treatment is directed towards suppressing the disease for many years, rather than curing it. The primary chemotherapeutic plan is [[polytherapy|combination]] chemotherapy with [[chlorambucil]] or [[cyclophosphamide]], plus a [[corticosteroid]] such as [[prednisone]] or [[prednisolone]]. The use of a corticosteroid has the additional benefit of suppressing some related autoimmune diseases, such as [[Warm autoimmune hemolytic anemia|immunohemolytic anemia]] or [[Idiopathic thrombocytopenic purpura|immune-mediated thrombocytopenia]]. In resistant cases, [[monotherapy|single-agent]] treatments with nucleoside drugs such as [[fludarabine]],<ref>{{cite journal | vauthors = Eichhorst BF, Busch R, Hopfinger G, Pasold R, Hensel M, Steinbrecher C, Siehl S, Jäger U, Bergmann M, Stilgenbauer S, Schweighofer C, Wendtner CM, Döhner H, Brittinger G, Emmerich B, Hallek M | title = Fludarabine plus cyclophosphamide versus fludarabine alone in first-line therapy of younger patients with chronic lymphocytic leukemia | journal = Blood | volume = 107 | issue = 3 | pages = 885–891 | date = February 2006 | pmid = 16219797 | doi = 10.1182/blood-2005-06-2395 | doi-access = free }}</ref> [[pentostatin]], or [[cladribine]] may be successful. Younger and healthier people may choose [[allogeneic]] or [[autologous]] [[bone marrow transplantation]] in the hope of a permanent cure.<ref>{{cite journal | vauthors = Gribben JG | title = Stem cell transplantation in chronic lymphocytic leukemia | journal = Biology of Blood and Marrow Transplantation | volume = 15 | issue = 1 Suppl | pages = 53–58 | date = January 2009 | pmid = 19147079 | pmc = 2668540 | doi = 10.1016/j.bbmt.2008.10.022 }}</ref>

===Acute myelogenous===
{{Further|Acute myeloid leukemia#Treatment}}

Many different anti-cancer drugs are effective for the treatment of AML. Treatments vary somewhat according to the age of the person and according to the specific subtype of AML. Overall, the strategy is to control bone marrow and systemic (whole-body) disease, while offering specific treatment for the central nervous system (CNS), if involved.<ref>{{Cite book | vauthors = Baig MQ |url=https://books.google.com/books?id=Dc8nDwAAQBAJ&pg=PA438 |title=Practical Radiotherapy & Chemotherapy Planning |date=2017-03-22 |publisher=JP Medical Ltd |isbn=978-93-86150-01-1 |language=en}}</ref>

In general, most oncologists rely on combinations of drugs for the initial, ''induction phase'' of chemotherapy. Such combination chemotherapy usually offers the benefits of early [[remission (medicine)|remission]] and a lower risk of disease resistance. ''Consolidation'' and ''maintenance'' treatments are intended to prevent disease recurrence. Consolidation treatment often entails a repetition of induction chemotherapy or the intensification of chemotherapy with additional drugs. By contrast, maintenance treatment involves drug doses that are lower than those administered during the induction phase.<ref>{{cite web|url=http://www.cancer.org/cancer/leukemia-acutemyeloidaml/detailedguide/leukemia-acute-myeloid-myelogenous-treating-typical-treatment-of-aml|title=Typical treatment of acute myeloid leukemia (except promyelocytic M3)|author=American Cancer Society|date=22 March 2012|work=Detailed Guide: Leukemia — Acute Myeloid (AML)|publisher=American Cancer Society|access-date=31 October 2012|url-status=live|archive-url=https://web.archive.org/web/20121112202809/http://www.cancer.org/cancer/leukemia-acutemyeloidaml/detailedguide/leukemia-acute-myeloid-myelogenous-treating-typical-treatment-of-aml|archive-date=12 November 2012}}</ref>

===Chronic myelogenous===
{{Further|Chronic myelogenous leukemia#Treatment}}

There are many possible treatments for CML, but the standard of care for newly diagnosed people is [[imatinib]] (Gleevec) therapy.<ref name="pmid17970609">{{cite journal | vauthors = Fausel C | title = Targeted chronic myeloid leukemia therapy: seeking a cure | journal = Journal of Managed Care Pharmacy | volume = 13 | issue = 8 Suppl A | pages = 8–12 | date = October 2007 | pmid = 17970609 | doi = 10.18553/jmcp.2007.13.s8-a.8 | pmc = 10437886 | url = http://www.amcp.org/data/jmcp/pages%208-12.pdf | url-status = dead | access-date = 18 May 2008 | archive-url = https://web.archive.org/web/20080528041331/http://www.amcp.org/data/jmcp/pages%208-12.pdf | archive-date = 28 May 2008 }}</ref> Compared to most anti-cancer drugs, it has relatively few side effects and can be taken [[Mouth|orally]] at home. With this drug, more than 90% of people will be able to keep the disease in check for at least five years,<ref name="pmid17970609"/> so that CML becomes a chronic, manageable condition.

In a more advanced, uncontrolled state, when the person cannot tolerate imatinib, or if the person wishes to attempt a permanent cure, then an allogeneic bone marrow transplantation may be performed. This procedure involves high-dose chemotherapy and radiation followed by infusion of bone marrow from a compatible donor. Approximately 30% of people die from this procedure.<ref name="pmid17970609"/>

===Hairy cell===
{{Further|Hairy cell leukemia#Treatment}}

'''Decision to treat'''<br />
People with hairy cell leukemia who are symptom-free typically do not receive immediate treatment. Treatment is generally considered necessary when the person shows signs and symptoms such as low blood cell counts (e.g., infection-fighting neutrophil count below 1.0&nbsp;K/μL), frequent infections, unexplained bruises, anemia, or fatigue that is significant enough to disrupt the person's everyday life.<ref>{{cite web |url=https://www.lecturio.com/concepts/hairy-cell-leukemia/| title=Hairy Cell Leukemia
|website=The Lecturio Medical Concept Library |access-date= 24 July 2021}}</ref>

'''Typical treatment approach'''<br />
People who need treatment usually receive either one week of [[cladribine]], given daily by intravenous infusion or a simple injection under the skin, or six months of [[pentostatin]], given every four weeks by intravenous infusion. In most cases, one round of treatment will produce a prolonged remission.<ref>{{cite journal | vauthors = Robak T, Jamroziak K, Gora-Tybor J, Blonski JZ, Kasznicki M, Dwilewicz-Trojaczek J, Wiater E, Zdunczyk A, Dybowicz J, Dmoszynska A, Wojtaszko M, Zdziarska B, Calbecka M, Kostyra A, Hellmann A, Lewandowski K, Stella-Holowiecka B, Sulek K, Gawronski K, Skotnicki AB, Nowak W, Zawilska K, Molendowicz-Portala L, Kloczko J, Sokolowski J, Warzocha K, Seferynska I, Ceglarek B, Konopka L | title = Cladribine in a weekly versus daily schedule for untreated active hairy cell leukemia: final report from the Polish Adult Leukemia Group (PALG) of a prospective, randomized, multicenter trial | journal = Blood | volume = 109 | issue = 9 | pages = 3672–5 | date = May 2007 | pmid = 17209059 | doi = 10.1182/blood-2006-08-042929 | doi-access = free }}</ref>

Other treatments include [[rituximab]] infusion or self-injection with [[Interferon-alpha]]. In limited cases, the person may benefit from ''[[splenectomy]]'' (removal of the [[spleen]]). These treatments are not typically given as the first treatment because their success rates are lower than cladribine or pentostatin.<ref>{{cite journal | vauthors = Saven A, Burian C, Adusumalli J, Koziol JA | title = Filgrastim for cladribine-induced neutropenic fever in patients with hairy cell leukemia | journal = Blood | volume = 93 | issue = 8 | pages = 2471–7 | date = April 1999 | pmid = 10194424 | doi = 10.1182/blood.V93.8.2471 }}</ref>

===T-cell prolymphocytic===
{{Further|T-cell prolymphocytic leukemia#Treatment}}

Most people with T-cell prolymphocytic leukemia, a rare and aggressive leukemia with a median survival of less than one year, require immediate treatment.<ref name="pmid11535503">{{cite journal | vauthors = Dearden CE, Matutes E, Cazin B, Tjønnfjord GE, Parreira A, Nomdedeu B, Leoni P, Clark FJ, Radia D, Rassam SM, Roques T, Ketterer N, Brito-Babapulle V, Dyer MJ, Catovsky D | title = High remission rate in T-cell prolymphocytic leukemia with CAMPATH-1H | journal = Blood | volume = 98 | issue = 6 | pages = 1721–6 | date = September 2001 | pmid = 11535503 | doi = 10.1182/blood.V98.6.1721 | s2cid = 26664911 | doi-access = free }}</ref>

T-cell prolymphocytic leukemia is difficult to treat, and it does not respond to most available chemotherapeutic drugs.<ref name="pmid11535503" /> Many different treatments have been attempted, with limited success in certain people: [[purine analogues]] (pentostatin, fludarabine, cladribine), [[chlorambucil]], and various forms of combination chemotherapy (cyclophosphamide, doxorubicin, vincristine, prednisone [[CHOP (chemotherapy)|CHOP]], cyclophosphamide, vincristine, prednisone [COP], vincristine, doxorubicin, prednisone, etoposide, cyclophosphamide, bleomycin [[VAPEC-B]]). [[Alemtuzumab]] (Campath), a [[monoclonal antibody]] that attacks white blood cells, has been used in treatment with greater success than previous options.<ref name="pmid11535503" />

Some people who successfully respond to treatment also undergo [[stem cell transplantation]] to consolidate the response.<ref name="pmid11535503" />

===Juvenile myelomonocytic===
Treatment for [[juvenile myelomonocytic leukemia]] can include [[splenectomy]], [[chemotherapy]], and [[bone marrow transplantation]].<ref>{{cite web|url=http://www.jmmlfoundation.org/modules.php?name=Content&pa=showpage&pid=8/ |title=JMMLfoundation.org |publisher=JMMLfoundation.org |access-date=29 August 2010 |url-status=dead |archive-url=https://web.archive.org/web/20090125041058/http://www.jmmlfoundation.org/modules.php?name=Content&pa=showpage&pid=8%2F |archive-date=25 January 2009 }}</ref>

==Prognosis==
The success of treatment depends on the type of leukemia and the age of the person. Outcomes have improved in the developed world.<ref name=WCR2014/> The average [[five-year survival rate]] is 65% in the United States.<ref name=SEER/> In children under 15, the five-year survival rate is greater (60 to 85%), depending on the type of leukemia.<ref name=ACS2014/> In children with acute leukemia who are cancer-free after five years, the cancer is unlikely to return.<ref name=ACS2014/>

Outcomes depend on whether it is acute or chronic, the specific abnormal white blood cell type, the presence and severity of [[anemia]] or [[thrombocytopenia]], the degree of tissue abnormality, the presence of [[metastasis]] and [[lymph node]] and [[bone marrow]] infiltration, the availability of therapies and the skills of the health care team. Treatment outcomes may be better when people are treated at larger centers with greater experience.<ref>{{cite journal | vauthors = Stock W | title = Adolescents and young adults with acute lymphoblastic leukemia | journal = Hematology. American Society of Hematology. Education Program | volume = 2010 | pages = 21–29 | date = 2010 | pmid = 21239766 | doi = 10.1182/asheducation-2010.1.21 | s2cid = 9796380 | doi-access = free }}</ref>

==Epidemiology==
[[File:Leukaemia world map-Deaths per million persons-WHO2012.svg|thumb|Deaths due to leukemia per million persons in 2012: {{Div col|small=yes|colwidth=10em}}{{legend|#ffff20|0–7}}{{legend|#ffe820|8–13}}{{legend|#ffd820|14–22}}{{legend|#ffc020|23–29}}{{legend|#ffa020|30–34}}{{legend|#ff9a20|35–39}}{{legend|#f08015|40–46}}{{legend|#e06815|47–64}}{{legend|#d85010|65–85}}{{legend|#d02010|86–132}}{{div col end}}|238x238px]]
In 2010, globally, approximately 281,500 people died of leukemia.<ref name=Loz2012>{{cite journal | vauthors = Lozano R, Naghavi M, Foreman K, Lim S, Shibuya K, Aboyans V, Abraham J, Adair T, Aggarwal R, Ahn SY, Alvarado M, Anderson HR, Anderson LM, Andrews KG, Atkinson C, Baddour LM, Barker-Collo S, Bartels DH, Bell ML, Benjamin EJ, Bennett D, Bhalla K, Bikbov B, Bin Abdulhak A, Birbeck G, Blyth F, Bolliger I, Boufous S, Bucello C, Burch M, Burney P, Carapetis J, Chen H, Chou D, Chugh SS, Coffeng LE, Colan SD, Colquhoun S, Colson KE, Condon J, Connor MD, Cooper LT, Corriere M, Cortinovis M, de Vaccaro KC, Couser W, Cowie BC, Criqui MH, Cross M, Dabhadkar KC, Dahodwala N, De Leo D, Degenhardt L, Delossantos A, Denenberg J, Des Jarlais DC, Dharmaratne SD, Dorsey ER, Driscoll T, Duber H, Ebel B, Erwin PJ, Espindola P, Ezzati M, Feigin V, Flaxman AD, Forouzanfar MH, Fowkes FG, Franklin R, Fransen M, Freeman MK, Gabriel SE, Gakidou E, Gaspari F, Gillum RF, Gonzalez-Medina D, Halasa YA, Haring D, Harrison JE, Havmoeller R, Hay RJ, Hoen B, Hotez PJ, Hoy D, Jacobsen KH, James SL, Jasrasaria R, Jayaraman S, Johns N, Karthikeyan G, Kassebaum N, Keren A, Khoo JP, Knowlton LM, Kobusingye O, Koranteng A, Krishnamurthi R, Lipnick M, Lipshultz SE, Ohno SL, Mabweijano J, MacIntyre MF, Mallinger L, March L, Marks GB, Marks R, Matsumori A, Matzopoulos R, Mayosi BM, McAnulty JH, McDermott MM, McGrath J, Mensah GA, Merriman TR, Michaud C, Miller M, Miller TR, Mock C, Mocumbi AO, Mokdad AA, Moran A, Mulholland K, Nair MN, Naldi L, Narayan KM, Nasseri K, Norman P, O'Donnell M, Omer SB, Ortblad K, Osborne R, Ozgediz D, Pahari B, Pandian JD, Rivero AP, Padilla RP, Perez-Ruiz F, Perico N, Phillips D, Pierce K, Pope CA, Porrini E, Pourmalek F, Raju M, Ranganathan D, Rehm JT, Rein DB, Remuzzi G, Rivara FP, Roberts T, De León FR, Rosenfeld LC, Rushton L, Sacco RL, Salomon JA, Sampson U, Sanman E, Schwebel DC, Segui-Gomez M, Shepard DS, Singh D, Singleton J, Sliwa K, Smith E, Steer A, Taylor JA, Thomas B, Tleyjeh IM, Towbin JA, Truelsen T, Undurraga EA, Venketasubramanian N, Vijayakumar L, Vos T, Wagner GR, Wang M, Wang W, Watt K, Weinstock MA, Weintraub R, Wilkinson JD, Woolf AD, Wulf S, Yeh PH, Yip P, Zabetian A, Zheng ZJ, Lopez AD, Murray CJ, AlMazroa MA, Memish ZA | title = Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010 | journal = Lancet | volume = 380 | issue = 9859 | pages = 2095–2128 | date = December 2012 | pmid = 23245604 | doi = 10.1016/S0140-6736(12)61728-0 | pmc = 10790329 | hdl-access = free | s2cid = 1541253 | hdl = 10536/DRO/DU:30050819 | url = https://repozitorij.upr.si/Dokument.php?id=7123&dn= }}</ref> In 2000, approximately 256,000 children and adults around the world developed a form of leukemia, and 209,000 died from it.<ref name=Numbers>{{cite journal|title=Cancer incidence, mortality and survival by site for 14 regions of the world| vauthors = Mathers CD, Boschi-Pinto C, Lopez AD, Murray CJ |journal=Global Programme on Evidence for Health Policy Discussion Paper No. 13|publisher=World Health Organization|year=2001|url=https://www.who.int/entity/healthinfo/paper13.pdf}}</ref> This represents about 3% of the almost seven million deaths due to cancer that year, and about 0.35% of all deaths from any cause.<ref name=Numbers /> Of the sixteen separate sites the body compared, leukemia was the 12th most common class of [[Neoplasm|neoplastic disease]] and the 11th most common cause of cancer-related death.<ref name=Numbers /> Leukemia occurs more commonly in the [[developed world]].<ref name=WCR2014/>

===United States===
About 245,000 people in the United States are affected with some form of leukemia, including those that have achieved remission or cure. Rates from 1975 to 2011 have increased by 0.7% per year among children.<ref>{{cite journal | vauthors = Amitay EL, Keinan-Boker L | title = Breastfeeding and Childhood Leukemia Incidence: A Meta-analysis and Systematic Review | journal = JAMA Pediatrics | volume = 169 | issue = 6 | pages = e151025 | date = June 2015 | pmid = 26030516 | doi = 10.1001/jamapediatrics.2015.1025 | doi-access = free }}</ref> Approximately 44,270 new cases of leukemia were diagnosed in the year 2008 in the US.<ref name=LLS>{{cite web | url = http://www.leukemia-lymphoma.org/all_page?item_id=9346 | title = Leukemia Facts & Statistics. | archive-url = https://web.archive.org/web/20090416060712/http://www.leukemia-lymphoma.org/all_page?item_id=9346 | archive-date=16 April 2009 | work = The Leukemia & Lymphoma Society. | access-date = 2 July 2009 }}</ref> This represents 2.9% of all cancers (excluding simple basal cell and squamous cell skin cancers) in the United States, and 30.4% of all [[blood cancer]]s.<ref>{{cite web|title=SEER Cancer Statistics Review, 1975–2006|work=Surveillance Epidemiology and End Results (SEER)|publisher=[[National Cancer Institute]]|url=http://seer.cancer.gov/csr/1975_2006/| veditors = Horner MJ, Ries LA, Krapcho M, Neyman N, etal |location=Bethesda, MD|access-date=3 November 2009|quote=Table 1.4: Age-Adjusted SEER Incidence and U.S. Death Rates and 5-Year Relative Survival Rates By Primary Cancer Site, Sex and Time Period|url-status=live|archive-url=https://web.archive.org/web/20090926004001/http://seer.cancer.gov/csr/1975_2006/|archive-date=26 September 2009}}</ref>

Among children with some form of cancer, about a third have a type of leukemia, most commonly [[acute lymphoblastic leukemia]].<ref name=LLS /> A type of leukemia is the second most common form of cancer in infants (under the age of 12 months) and the most common form of cancer in older children.<ref name="SEER1999">{{cite book | vauthors = Gurney JG, Smith MA, Ross JA | date = 1999 | title = Cancer Incidence and Survival among Children and Adolescents, United States SEER program 1975–1995 | chapter-url = http://www.seer.cancer.gov/publications/childhood/leukemia.pdf | chapter = Leukemia | archive-url = https://web.archive.org/web/20101224153901/http://seer.cancer.gov/publications/childhood/leukemia.pdf | archive-date=24 December 2010 | publisher = Cancer Statistics Branch, National Cancer Institute }}</ref> Boys are somewhat more likely to develop leukemia than girls, and white American children are almost twice as likely to develop leukemia than black American children.<ref name="SEER1999" /> Only about 3% cancer diagnoses among adults are for leukemias, but because cancer is much more common among adults, more than 90% of all leukemias are diagnosed in adults.<ref name=LLS />

[[Race (human classification)|Race]] is a [[Risk factor (epidemiology)|risk factor]] in the United States.  [[Hispanic]]s, especially those under the age of 20, are at the highest risk for leukemia, while [[White people|whites]], [[Indigenous peoples of the Americas|Native Americans]], [[Asian Americans]], and [[Alaska Natives]] are at higher risk than [[African Americans]].<ref>{{cite web | url = http://www.lls.org/diseaseinformation/getinformationsupport/factsstatistics/childhoodbloodcancers/ | title = Childhood Blood Cancers | work = The Leukemia & Lymphoma Society | archive-url = https://web.archive.org/web/20120905211115/http://www.lls.org/diseaseinformation/getinformationsupport/factsstatistics/childhoodbloodcancers/ | archive-date = 5 September 2012 }}</ref>

More men than women are diagnosed with leukemia and die from the disease. Around 30 percent more men than women have leukemia.<ref>{{cite web | url = http://www.lls.org/content/nationalcontent/resourcecenter/freeeducationmaterials/generalcancer/pdf/facts.pdf/ | title = Facts 2012 | work = The Leukemia & Lymphoma Society | archive-url = https://web.archive.org/web/20121014092708/http://www.lls.org/content/nationalcontent/resourcecenter/freeeducationmaterials/generalcancer/pdf/facts.pdf | archive-date=14 October 2012 }}</ref>

===Australia===
In Australia, leukemia is the eleventh most common cancer.<ref name="CancerAustralia">{{cite web|url=https://www.canceraustralia.gov.au/cancer-types/leukaemia/statistics|title=Leukaemia in Australia statistics|work=canceraustralia.gov.au|date=2023|accessdate=3 April 2023}}</ref> In 2014–2018, Australians diagnosed with leukemia had a 64% chance (65% for males and 64% for females) of surviving for five years compared to the rest of the Australian population–there was a 21% increase in survival rates between 1989–1993.<ref name="CancerAustralia" />

===UK===
Overall, leukemia is the eleventh most common cancer in the UK (around 8,600 people were diagnosed with the disease in 2011), and it is the ninth most common cause of cancer death (around 4,800 people died in 2012).<ref>{{cite web|title=Leukaemia (all subtypes combined) statistics|url=http://www.cancerresearchuk.org/cancer-info/cancerstats/types/leukaemia/|website=Cancer Research UK|access-date=27 October 2014|url-status=live|archive-url=https://web.archive.org/web/20141007152651/http://www.cancerresearchuk.org/cancer-info/cancerstats/types/leukaemia/|archive-date=7 October 2014}}</ref>

==History==
[[File:Rudolf Virchow.jpg|thumb|alt=Photo of the upper body of a bespectacled man|Rudolf Virchow]]
Leukemia was first described by anatomist and surgeon [[Alfred-Armand-Louis-Marie Velpeau]] in 1827. A more complete description was given by pathologist [[Rudolf Virchow]] in 1845. Around ten years after Virchow's findings, pathologist [[Franz Ernst Christian Neumann]] found that the bone marrow of a deceased person with leukemia was colored "dirty green-yellow" as opposed to the normal red. This finding allowed Neumann to conclude that a bone marrow problem was responsible for the abnormal blood of people with leukemia.<ref>{{Cite journal |last=Thomas |first=Xavier |date=2013-08-06 |title=First contributors in the history of leukemia |journal=World Journal of Hematology |language=en |volume=2 |issue=3 |pages=62–70 |doi=10.5315/wjh.v2.i3.62|doi-access=free }}</ref>

By 1900, leukemia was viewed as a family of diseases as opposed to a single disease. By 1947, Boston pathologist [[Sidney Farber]] believed from past experiments that [[aminopterin]], a folic acid mimic, could potentially cure leukemia in children. The majority of the children with ALL who were tested showed signs of improvement in their bone marrow, but none of them were actually cured. Nevertheless, this result did lead to further experiments.<ref>{{cite journal | vauthors = Ribatti D | title = Sidney Farber and the treatment of childhood acute lymphoblastic leukemia with a chemotherapeutic agent | journal = Pediatric Hematology and Oncology | volume = 29 | issue = 4 | pages = 299–302 | date = May 2012 | pmid = 22568792 | doi = 10.3109/08880018.2012.678969 | s2cid = 31176962 }}</ref>

In 1962, researchers Emil J. Freireich, Jr. and Emil Frei III used combination chemotherapy to attempt to cure leukemia. The tests were successful with some people surviving long after the tests.<ref>{{cite journal | vauthors = Patlak M | title = Targeting leukemia: from bench to bedside | journal = FASEB Journal | volume = 16 | issue = 3 | pages = 273 | date = March 2002 | pmid = 11874976 | doi = 10.1096/fj.02-0029bkt | doi-access = free | s2cid = 221751708 }}</ref>

===Etymology===
Observing an abnormally large number of white blood cells in a blood sample from a person, Virchow called the condition ''Leukämie'' in [[German (language)|German]], which he formed from the two [[Greek language|Greek]] words ''leukos'' ([[wikt:λευκός|λευκός]]), meaning 'white', and ''haima'' ([[wikt:αἷμα|αἷμα]]), meaning 'blood'.<ref name="MedlinePlus 2019">{{cite web | title=Leukemia: MedlinePlus Medical Encyclopedia | website=MedlinePlus | date=8 May 2019 | url=https://medlineplus.gov/ency/article/001299.htm | access-date=16 May 2019}}</ref> It was formerly also called ''leucemia''.<ref name="etymology">{{cite web |title=leukemia |url=https://www.etymonline.com/word/leukemia |website=Online Etymology Dictionary |access-date=14 February 2023}}</ref>

==Society and culture==
According to [[Susan Sontag]], leukemia was often romanticized in 20th-century fiction, portrayed as a joy-ending, clean disease whose fair, innocent and gentle victims die young or at the wrong time. As such, it was the cultural successor to [[Tuberculosis#Folklore|tuberculosis]], which held this cultural position until it was discovered to be an infectious disease.<ref>{{cite book| vauthors = Sontag S |title=Illness as Metaphor|publisher=Farrar, Straus and Giroux|location=New York|year=1978|pages=[https://archive.org/details/illnessasmetapho00susa/page/18 18]|isbn=978-0-374-17443-9|title-link=Illness as Metaphor}}</ref> The 1970 romance novel ''[[Love Story (novel)|Love Story]]'' is an example of this romanticization of leukemia.<ref>{{Cite thesis| vauthors = Bey B |title=Cancer as Metaphor: The Metaphorical Implications of Romanticized Illness in Young Adult Fiction|date=2017|degree=English Honors|publisher=[[Trinity University (Texas)|Trinity University]]|url=https://digitalcommons.trinity.edu/cgi/viewcontent.cgi?article=1027&context=eng_honors|page=5-6}}</ref>

In the United States, around $5.4 billion is spent on treatment a year.<ref name="NCISnap2">{{cite web|title = A Snapshot of Leukemia|url = http://www.cancer.gov/researchandfunding/snapshots/leukemia|website = NCI|access-date = 18 June 2014|url-status = live|archive-url = https://web.archive.org/web/20140704183430/http://www.cancer.gov/researchandfunding/snapshots/leukemia|archive-date = 4 July 2014|df = dmy-all}}</ref>

==Research directions==
Significant research into the causes, prevalence, diagnosis, treatment, and prognosis of leukemia is being performed. Hundreds of [[clinical trials]] are being planned or conducted at any given time.<ref>{{cite web|url=http://www.clinicaltrials.gov/ct2/results?term=leukemia|title=Search of: leukemia&nbsp;— List Results&nbsp;— ClinicalTrials.gov|url-status=live|archive-url=https://web.archive.org/web/20100915043150/http://clinicaltrials.gov/ct2/results?term=Leukemia|archive-date=15 September 2010}}</ref> Studies may focus on effective means of treatment, better ways of treating the disease, improving the quality of life for people, or appropriate care in [[Remission (medicine)|remission]] or after cures.<ref>{{Cite web |title=Learn About Clinical Studies — Reasons for Conducting Clinical Studies |url=https://clinicaltrials.gov/ct2/about-studies/learn#ReasonsForConducting |access-date=2023-03-03 |website=Clinicaltrials.gov |language=en}}</ref>

In general, there are two types of leukemia research: clinical or [[translational research]] and [[basic research]]. Clinical/translational research focuses on studying the disease in a defined and generally immediately applicable way, such as testing a new drug in people.  By contrast, basic science research studies the disease process at a distance, such as seeing whether a suspected carcinogen can cause leukemic changes in isolated cells in the laboratory or how the DNA changes inside leukemia cells as the disease progresses.  The results from basic research studies are generally less immediately useful to people with the disease.<ref>{{cite web|title=Understanding Clinical Trials for Blood Cancers|url=http://www.leukemia-lymphoma.org/attachments/National/br_1162487596.pdf|publisher=Leukemia and Lymphoma Society|access-date=19 May 2010|url-status=dead|archive-url=https://web.archive.org/web/20110105213515/http://www.leukemia-lymphoma.org/attachments/National/br_1162487596.pdf|archive-date=5 January 2011}}</ref>

Treatment through [[gene therapy]] is currently being pursued. One such approach used genetically modified [[T cell]]s, known as [[chimeric antigen receptor T cell]]s (CAR-T cells), to attack cancer cells. In 2011, a year after treatment, two of the three people with advanced chronic lymphocytic leukemia were reported to be cancer-free<ref>{{cite web| vauthors = Jaslow R |title=New Leukemia Therapy Destroys Cancer by Turning Blood Cells into "Assassins"|date=11 August 2011 |url=http://www.cbsnews.com/news/new-leukemia-therapy-destroys-cancer-by-turning-blood-cells-into-assassins/|publisher=CBSnews.com HealthPop section|access-date=11 August 2011|url-status=live|archive-url=https://web.archive.org/web/20140331173850/http://www.cbsnews.com/news/new-leukemia-therapy-destroys-cancer-by-turning-blood-cells-into-assassins/|archive-date=31 March 2014}}</ref> and in 2013, three of five subjects who had acute lymphocytic leukemia were reported to be in remission for five months to two years.<ref name=SloanKettering>{{cite web | vauthors = Coghlan A | date = 26 March 2013 | url = https://www.newscientist.com/article/mg21729104.100-gene-therapy-cures-leukaemia-in-eight-days.html | title = Gene therapy cures leukaemia in eight days | archive-url = https://web.archive.org/web/20150515211530/http://www.newscientist.com/article/mg21729104.100-gene-therapy-cures-leukaemia-in-eight-days.html | archive-date=15 May 2015 | work = The New Scientist | access-date = 15 April 2013 }}</ref> Subsequent studies with a variety of CAR-T types continue to be promising.<ref name=":0">{{cite journal | vauthors = Zhao J, Song Y, Liu D | title = Clinical trials of dual-target CAR T cells, donor-derived CAR T cells, and universal CAR T cells for acute lymphoid leukemia | journal = Journal of Hematology & Oncology | volume = 12 | issue = 1 | pages = 17 | date = February 2019 | pmid = 30764841 | pmc = 6376657 | doi = 10.1186/s13045-019-0705-x | doi-access = free }}</ref> As of 2018, two CAR-T therapies have been approved by the [[Food and Drug Administration]]. CAR-T treatment has significant side effects,<ref>{{cite journal | vauthors = Zheng PP, Kros JM, Li J | title = Approved CAR T cell therapies: ice bucket challenges on glaring safety risks and long-term impacts | journal = Drug Discovery Today | volume = 23 | issue = 6 | pages = 1175–82 | date = June 2018 | pmid = 29501911 | doi = 10.1016/j.drudis.2018.02.012 | doi-access = free | hdl = 1765/105338 | hdl-access = free }}</ref> and loss of the [[antigen]] targeted by the CAR-T cells is a common mechanism for relapse.<ref name=":0" /> The stem cells that cause different types of leukemia are also being researched.<ref>{{cite web|publisher=[[Leukaemia & Lymphoma Research]]|title=How we're beating leukaemia|url=http://leukaemialymphomaresearch.org.uk/research/how-were-beating-blood-cancers/how-were-beating-leukaemia|access-date=24 September 2013|url-status=live|archive-url=https://web.archive.org/web/20130927031151/http://leukaemialymphomaresearch.org.uk/research/how-were-beating-blood-cancers/how-were-beating-leukaemia|archive-date=27 September 2013}}</ref>

==Pregnancy==
Leukemia is rarely associated with pregnancy, affecting only about 1 in 10,000 pregnant women.<ref name=Shapira /> How it is handled depends primarily on the type of leukemia. Nearly all leukemias appearing in pregnant women are acute leukemias.<ref name=Koren>{{cite journal | vauthors = Koren G, Lishner M | title = Pregnancy and commonly used drugs in hematology practice | journal = Hematology. American Society of Hematology. Education Program | volume = 2010 | pages = 160–5 | year = 2010 | pmid = 21239787 | doi = 10.1182/asheducation-2010.1.160 | s2cid = 21832575 | doi-access = free }}</ref> Acute leukemias normally require prompt, aggressive treatment, despite significant risks of [[Miscarriage|pregnancy loss]] and [[Congenital disorder|birth defects]], especially if chemotherapy is given during the developmentally sensitive [[first trimester]].<ref name=Shapira/> Chronic myelogenous leukemia can be treated with relative safety at any time during pregnancy with [[Interferon-alpha]] hormones.<ref name=Shapira /> Treatment for chronic lymphocytic leukemias, which are rare in pregnant women, can often be postponed until after the end of the pregnancy.<ref name=Shapira>{{cite journal | vauthors = Shapira T, Pereg D, Lishner M | title = How I treat acute and chronic leukemia in pregnancy | journal = Blood Reviews | volume = 22 | issue = 5 | pages = 247–259 | date = September 2008 | pmid = 18472198 | doi = 10.1016/j.blre.2008.03.006 }}</ref><ref name=Koren />

== See also ==
* [[Acute erythroid leukemia]]
* [[Antileukemic drug]]s, medications used to kill leukemia cells
* [[Cancer-related fatigue]]
* [[Hematologic disease]]s, the large class of blood-related disorders, including leukemia
* [[Multiple myeloma]]

== References ==
{{Reflist}}

== External links ==
{{commons category|Leukemias}}
* [http://www.cancerhelp.org.uk/type/leukaemia/ Leukaemia information] from [[Cancer Research UK]]

{{Medical condition classification and resources
 |ICD11 = {{ICD11|2A40}}, {{ICD11|2A41}}, {{ICD11|2A42}}, {{ICD11|2A60}}, {{ICD11|2A82}}, {{ICD11|2A83.4}}, {{ICD11|2B33}}
 |ICD10 = {{ICD10|C91}}–{{ICD10|C95}}
 |ICD9 = {{ICD9|208.9}}
 |ICDO = 9800–9940
 |OMIM =
 |MedlinePlus=001299
 |eMedicineSubj=article
 |eMedicineTopic=1201870
 |DiseasesDB = 7431
 |MeshID = D007938
 |Scholia = Q29496
}}
{{Lymphoid malignancy}}
{{Myeloid malignancy|us=y}}
{{Authority control}}

[[Category:Leukemia| ]]
[[Category:Articles containing video clips]]
[[Category:Lymphatic vessel diseases]]
[[Category:Wikipedia medicine articles ready to translate]]