JMML accounts for 1-2% of childhood leukemias each year; in the United States, an estimated 25-50 new cases are diagnosed each year, which also equates to about 3 cases per million children. There is no known environmental cause for JMML. Since about 10% of patients are diagnosed before 3 months of age, it is thought that JMML is a congenital condition in these infants

The role of chemotherapy or other pharmacologic treatments against JMML before bone marrow transplant has not been studied completely and its importance is still unknown. Chemotherapy by itself has proven unable to bring about long-term survival in JMML.

- Low-dose conventional chemotherapy: Studies have shown no influence from low-dose conventional chemotherapy on JMML patients’ length of survival. Some combinations of 6-mercaptopurine with other chemotherapy drugs have produced results such as decrease in organ size and increase or normalization of platelet and leukocyte count.

- Intensive chemotherapy: Complete remission with ongoing durability from JMML has not been possible through use of intensive chemotherapy, but it is still used at times because it has improved the condition of a small but significant number of JMML patients who do not display an aggressive disease. The COG JMML study administers 2 cycles of fludarabine and cytarabine for 5 consecutive days along with 13-cis retinoic acid during and afterwards. The EWOG-MDS JMML study, however, does not recommend intensive chemotherapy before bone marrow transplant.

- 13-cis retinoic acid (Isotretinoin): In the lab, 13-cis-retinoic acid has inhibited the growth of JMML cells. The COG JMML study therefore includes 13-cis-retinoic acid in its treatment protocol, though its therapeutic value for JMML remains controversial.

The treatment of CMML remains challenging due to the lack of clinical trials investigating the disease as its own clinical entity. It is often grouped with MDS in clinical trials, and for this reason the treatment of CMML is very similar to that of MDS. Most cases are dealt with as supportive rather than curative because most therapies do not effectively increase survival. Indications for treatment include the presence of B symptoms, symptomatic organ involvement, increasing blood counts, hyperleukocytosis, leukostasis and/or worsening cytopaenias.

Blood transfusions and EPO administration are used to raise haemoglobin levels in cases with anaemia.

Azacitidine is a drug approved by the US Food & Drug Administration (FDA) for the treatment of CMML and by the European Medicines Agency for high risk non-proliferative CMML with 10-19% marrow blasts. It is a cytidine analogue that causes hypomethylation of DNA by inhibition of DNA methyltransferase. Decitabine is a similar drug to azacitidine and is approved by the FDA for treatments of all subtypes of MDS, including CMML. Hydroxyurea is a chemotherapy that is used in the myeloproliferative form of CMML to reduce cell numbers.

Haematopoietic stem cell transplant remains the only curative treatment for CMML. However, due to the late age of onset and presence of other illnesses, this form of treatment is often not possible.

Leukemia is rarely associated with pregnancy, affecting only about 1 in 10,000 pregnant women. How it is handled depends primarily on the type of leukemia. Acute leukemias normally require prompt, aggressive treatment, despite significant risks of pregnancy loss and birth defects, especially if chemotherapy is given during the developmentally sensitive first trimester.

Treatment for erythroleukemia generally follows that for other types of AML, not otherwise specified. It consists of chemotherapy, frequently consisting of

cytarabine, daunorubicin, and idarubicin. It can also involve bone marrow transplantation.

The treatment a child will undergo is based on the child's age, overall health, medical history, their tolerance for certain medications, procedures, and therapies, along with the parents' opinion and preference.

- Chemotherapy is a treatment that uses drugs to interfere with the cancer cells ability to grow and reproduce. Chemotherapy can be used alone or in combination with other therapies. Chemotherapy can be given either as a pill to swallow orally, an injection into the fat or muscle, through an IV directly into the bloodstream, or directly into the spinal column.

- A stem cell transplant is a process by which healthy cells are infused into the body. A stem-cell transplant can help the human body make enough healthy white blood cells, red blood cells, or platelets, and reduce the risk of life-threatening infections, anemia, and bleeding. It is also known as a bone-marrow transplant or an umbilical-cord blood transplant, depending on the source of the stem cells. Stem cell transplants can use the cells from the same person, called an autologous stem cell transplant or they can use stem cells from other people, known as an allogenic stem cell transplant. In some cases, the parents of a child with childhood leukemia may conceive a saviour sibling by preimplantation genetic diagnosis to be an appropriate match for the HLA antigen.

Before the advent of tyrosine kinase inhibitors, the median survival time for CML patients had been about 3–5 years from time of diagnosis.

With the use of tyrosine kinase inhibitors, survival rates have improved dramatically. A 2006 followup of 553 patients using imatinib (Gleevec) found an overall survival rate of 89% after five years.

A 2011 followup of 832 patients using imatinib who achieved a stable cytogenetic response found an overall survival rate of 95.2% after 8 years, which is similar to the rate in the general population. Fewer than 1% of patients died because of leukemia progression.

Leukemia is rarely associated with pregnancy, affecting only about 1 in 10,000 pregnant women. How it is handled depends primarily on the type of leukemia. Nearly all leukemias appearing in pregnant women are acute leukemias. Acute leukemias normally require prompt, aggressive treatment, despite significant risks of pregnancy loss and birth defects, especially if chemotherapy is given during the developmentally sensitive first trimester. Chronic myelogenous leukemia can be treated with relative safety at any time during pregnancy with Interferon-alpha hormones. Treatment for chronic lymphocytic leukemias, which are rare in pregnant women, can often be postponed until after the end of the pregnancy.

CML accounts for 8% of all leukaemias in the UK, and around 680 people were diagnosed with the disease in 2011.

Leukemia is rarely associated with pregnancy, affecting only about one in 10,000 pregnant women. Treatment for chronic lymphocytic leukemias can often be postponed until after the end of the pregnancy. If treatment is necessary, then giving chemotherapy during the second or third trimesters is less likely to result in pregnancy loss or birth defects than treatment during the first trimester.

There have been few individual epidemiological studies of CMML, due to the difficulty in the disease classification. CMML has an estimated incidence of less than 1 per 100,000 persons per year.

The median age of diagnosis is 65–75. CMML has a propensity for males rather than females, at a ratio of 1.5–3:1.

While investigational drug therapies exist, no curative drug treatment exists for any of the MPDs. The goal of treatment for ET and PV is prevention of thrombohemorrhagic complications. The goal of treatment for MF is amelioration of anemia, splenomegaly, and other symptoms. Low-dose aspirin is effective in PV and ET. Tyrosine kinase inhibitors like imatinib have improved the prognosis of CML patients to near-normal life expectancy.

Recently, a "JAK2" inhibitor, namely ruxolitinib, has been approved for use in primary myelofibrosis. Trials of these inhibitors are in progress for the treatment of the other myeloproliferative neoplasms.

Acute erythroid leukemia is rare, accounting for only 3–5% of all acute myeloid leukemia cases. One study estimated an occurrence rate of 0.077 cases per 100,000 people each year. 64–70% of people with this condition are male, and most are elderly, with a median age of 65.

As described above, chloromas should always be considered manifestations of systemic disease, rather than isolated local phenomena, and treated as such. In the patient with newly diagnosed leukemia and an associated chloroma, systemic chemotherapy against the leukemia is typically used as the first-line treatment, unless an indication for local treatment of the chloroma (e.g. compromise of the spinal cord) emerges. Chloromas are typically quite sensitive to standard antileukemic chemotherapy. Allogeneic hematopoietic stem cell transplantation should be considered in fit patients with suitable available donor, as long term remissions have been reported.

If the chloroma is persistent after completion of induction chemotherapy, local treatment, such as surgery or radiation therapy, may be considered, although neither has an effect on survival.

Patients presenting with a primary chloroma typically receive systemic chemotherapy, as development of acute leukemia is nearly universal in the short term after detection of the chloroma.

Patients treated for acute leukemia who relapse with an isolated chloroma are typically treated with systemic therapy for relapsed leukemia. However, as with any relapsed leukemia, outcomes are unfortunately poor.

Patients with "preleukemic" conditions, such as myelodysplastic syndromes or myeloproliferative syndromes, who develop a chloroma are often treated as if they have transformed to acute leukemia.

First-line treatment of AML consists primarily of chemotherapy, and is divided into two phases: induction and postremission (or consolidation) therapy. The goal of induction therapy is to achieve a complete remission by reducing the number of leukemic cells to an undetectable level; the goal of consolidation therapy is to eliminate any residual undetectable disease and achieve a cure. Hematopoietic stem cell transplantation is usually considered if induction chemotherapy fails or after a person relapses, although transplantation is also sometimes used as front-line therapy for people with high-risk disease. Efforts to use tyrosine kinase inhibitors in AML continue.

The Hairy Cell Leukemia Consortium was founded in 2008 to address researchers' concerns about the long-term future of research on the disease. Partly because existing treatments are so successful, the field has attracted very few new researchers.

In 2013 the Hairy Cell Leukemia Foundation was created when the Hairy Cell Leukemia Consortium and the Hairy Cell Leukemia Research Foundation joined together. The HCLF is dedicated to improving outcomes for patients by advancing research into the causes and treatment of hairy cell leukemia, as well as by providing educational resources and comfort to all those affected by hairy cell leukemia.

Three immunotoxin drugs have been studied in patients at the NIHNational Cancer Institute in the U.S.: BL22, HA22 and LMB-2. All of these protein-based drugs combine part of an anti-B cell antibody with a bacterial toxin to kill the cells on internalization. BL22 and HA22 attack a common protein called CD22, which is present on hairy cells and healthy B cells. LMB-2 attacks a protein called CD25, which is not present in HCL-variant, so LMB-2 is only useful for patients with HCL-classic or the Japanese variant. HA-22, now renamed moxetumab pasudotox, is being studied in patients with relapsed hairy cell leukemia at the National Cancer Institute in Bethesda, Maryland, MD Anderson Cancer Center in Houston, Texas, and Ohio State University in Columbus, Ohio. Other sites for the study are expected to start accepting patients in late 2014, including The Royal Marsden Hospital in London, England.

Other clinical trials are studying the effectiveness of cladribine followed by rituximab in eliminating residual hairy cells that remain after treatment by cladribine or pentostatin. It is not currently known if the elimination of such residual cells will result in more durable remissions.

BRAF mutation has been frequently detected in HCL (Tiacci et al. NEJM 2011) and some patients may respond to Vemurafenib

The major remaining research questions are identifying the cause of HCL and determining what prevents hairy cells from maturing normally.

CLL treatment focuses on controlling the disease and its symptoms rather than on an outright cure. CLL is treated by chemotherapy, radiation therapy, biological therapy, or bone marrow transplantation. Symptoms are sometimes treated surgically (splenectomy – removal of enlarged spleen) or by radiation therapy ("de-bulking" swollen lymph nodes).

Initial CLL treatments vary depending on the exact diagnosis and the progression of the disease, and even with the preference and experience of the health care practitioner. Any of dozens of agents may be used for CLL therapy. An initial treatment regimen that contains fludarabine, cyclophosphamide, and rituximab (known as FCR) has demonstrated higher overall response rates and complete response rates.

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. Studies may focus on effective means of treatment, better ways of treating the disease, improving the quality of life for patients, or appropriate care in remission or after cures.

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 patient-applicable way, such as testing a new drug in patients. 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 patients with the disease.

Treatment through gene therapy is currently being pursued. One such approach used genetically modified T cells to attack cancer cells. In 2011, a year after treatment, two of the three patients with advanced chronic lymphocytic leukemia were reported to be cancer-free and in 2013, three of five subjects who had acute lymphocytic leukemia were reported to be in remission for five months to two years. Identifying stem cells that cause different types of leukaemia is also being researched.

Several treatments are available, and successful control of the disease is common.

Not everyone needs treatment immediately. Treatment is usually given when the symptoms of the disease interfere with the patient's everyday life, or when white blood cell or platelet counts decline to dangerously low levels, such as an absolute neutrophil count below one thousand cells per microliter (1.0 K/uL). Not all patients need treatment immediately upon diagnosis.

Treatment delays are less important than in solid tumors. Unlike most cancers, treatment success does not depend on treating the disease at an early stage. Because delays do not affect treatment success, there are no standards for how quickly a patient should receive treatment. However, waiting too long can cause its own problems, such as an infection that might have been avoided by proper treatment to restore immune system function. Also, having a higher number of hairy cells at the time of treatment can make certain side effects somewhat worse, as some side effects are primarily caused by the body's natural response to the dying hairy cells. This can result in the hospitalization of a patient whose treatment would otherwise be carried out entirely at the hematologist's office.

Single-drug treatment is typical. Unlike most cancers, only one drug is normally given to a patient at a time. While monotherapy is normal, combination therapy—typically using one first-line therapy and one second-line therapy—is being studied in current clinical trials and is used more frequently for refractory cases. Combining rituximab with cladribine or pentostatin may or may not produce any practical benefit to the patient. Combination therapy is almost never used with a new patient. Because the success rates with purine analog monotherapy are already so high, the additional benefit from immediate treatment with a second drug in a treatment-naïve patient is assumed to be very low. For example, one round of either cladribine or pentostatin gives the median first-time patient a decade-long remission; the addition of rituximab, which gives the median patient only three or four years, might provide no additional value for this easily treated patient. In a more difficult case, however, the benefit from the first drug may be substantially reduced and therefore a combination may provide some benefit.

Natural killer (NK) cell therapy is used in pediatrics for children with relapsed lymphoid leukemia. These patients normally have a resistance to chemotherapy, therefore, in order to continue on, must receive some kind of therapy. In some cases, NK cell therapy is a choice.

NK cells are known for their ability to eradicate tumor cells without any prior sensitization to them. One problem when using NK cells in order to fight off lymphoid leukemia is the fact that it is hard to amount enough of them to be effective. One can receive donations of NK cells from parents or relatives through bone marrow transplants. There are also the issues of cost, purity and safety. Unfortunately, there is always the possibility of Graft vs host disease while transplanting bone marrow.

NK cell therapy is a possible treatment for many different cancers such as Malignant glioma.

T-PLL is an extremely rare aggressive disease, and patients are not expected to live normal lifespans. Before the recent introduction of better treatments, such as alemtuzumab, the median survival time was 7.5 months after diagnosis. More recently, some patients have survived five years and more, although the median survival is still low.

Most patients with T-cell prolymphocytic leukemia require immediate treatment.

T-cell prolymphocytic leukemia is difficult to treat, and it does not respond to most available chemotherapeutic drugs. Many different treatments have been attempted, with limited success in certain patients: purine analogues (pentostatin, fludarabine, cladribine), chlorambucil, and various forms of combination chemotherapy regimens, including cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP), etoposide, bleomycin (VAPEC-B).

Alemtuzumab (Campath), an anti-CD52 monoclonal antibody that attacks white blood cells, has been used in treatment with greater success than previous options. In one study of previously treated people with T-PLL, people who had a complete response to alemtuzumab survived a median of 16 months after treatment.

Some patients who successfully respond to treatment also undergo stem cell transplantation to consolidate the response.

ANKL is treated similarly to most B-cell lymphomas. Anthracycline-containing chemotherapy regimens are commonly offered as the initial therapy. Some patients may receive a stem cell transplant.

Most patients will die 2 years after diagnosis.

If treatment has been successful ("complete" or "partial remission"), a person is generally followed up at regular intervals to detect recurrence and monitor for "secondary malignancy" (an uncommon side-effect of some chemotherapy and radiotherapy regimens—the appearance of another form of cancer). In the follow-up, which should be done at pre-determined regular intervals, general anamnesis is combined with complete blood count and determination of lactate dehydrogenase or thymidine kinase in serum.

The exact cause of most cases of childhood leukemia is not known. Most children with leukemia do not have any known risk factors. The immune system plays an important role in protecting the body's immune system. An alteration or defect in the immune system may increase the risk for developing cancer. The immune system can be damaged by different factors, such as exposure to different viruses, environmental factors, chemical factors and other various infections.

There also appears to be some evidence linking childhood leukemia to x-ray exposure. In a 2010 study by the University of California, Berkeley’s School of Public Health, researchers found that children with acute lymphoid leukemia (ALL) had almost twice the chance of having been exposed to three or more X-rays compared with children who did not have leukemia.