Leukemia Totally Explained

Everything about Leukemia totally explained

- | ICD9 = | ICDO = 9800-9940 | Image = acute_leukemia-ALL.jpg | Caption = A Wright's stained bone marrow aspirate smear of patient with precursor B-cell acute lymphoblastic leukemia.| OMIM = | MedlinePlus = | eMedicineSubj = | eMedicineTopic = | DiseasesDB = 7431 | MeshID = D007938 | }}
Leukemia or leukaemia (Greek leukos λευκός, "white"; aima αίμα, "blood") is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells (leukocytes). It is part of the broad group of diseases called hematological neoplasms.

Classification

Leukemia is a broad term covering a spectrum of diseases. Leukemia is cancer in the blood.
Leukemia is clinically and pathologically split into its acute and chronic forms.

Acute leukemia is characterized by the rapid increase of immature blood cells. This crowding makes the bone marrow unable to produce healthy blood cells. Acute forms of leukemia can occur in children and young adults. (In fact, it's a more common cause of death for children in the US than any other type of malignant disease). Immediate treatment is required in acute leukemias due to the rapid progression and accumulation of the malignant cells, which then spill over into the bloodstream and spread to other organs of the body. Central nervous system (CNS) involvement is uncommon, although the disease can occasionally cause cranial nerve palsies.
Chronic leukemia is distinguished by the excessive build up of relatively mature, but still abnormal, blood cells. Typically taking months to years to progress, the cells are produced at a much higher rate than normal cells, resulting in many abnormal white blood cells in the blood. Chronic leukemia mostly occurs in older people, but can theoretically occur in any age group. Whereas acute leukemia must be treated immediately, chronic forms are sometimes monitored for some time before treatment to ensure maximum effectiveness of therapy.

Furthermore, the diseases are classified into lymphoblastic or lymphocytic leukemias, which indicate that the cancerous change took place in a type of marrow cell that normally goes on to form lymphocytes, and myeloid or myelogenous leukemias, which indicate that the cancerous change took place in a type of marrow cell that normally goes on to form red cells, some types of white cells, and platelets.
Combining these two classifications provides a total of four main categories:

Cell type	Acute	Chronic
Lymphocytic leukemia (or "lymphoblastic")	Acute lymphocytic leukemia (ALL)	Chronic lymphocytic leukemia (CLL)
Myelogenous leukemia (also "myeloid" or "nonlymphocytic")	Acute myelogenous leukemia (AML)	Chronic myelogenous leukemia (CML)

Within these main categories, there are typically several subcategories. Types outside these main categories include hairy cell leukemia.

Comparison of leukemia types

Acute lymphocytic leukemia (ALL) is the most common type of leukemia in young children. This disease also affects adults, especially those age 65 and older. Standard treatments involve chemotherapy and radiation. The survival rates vary by age: 85% in children and 50% in adults.

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 75%. It is incurable, but there are many effective treatments.

Acute myelogenous leukemia (AML) occurs more commonly in adults than in children, and more commonly in men than women. AML is treated with chemotherapy. The five-year survival rate is 40%.

Chronic myelogenous leukemia (CML) occurs mainly in adults. A very small number of children also develop this disease. Treatment is with imatinib (Gleevec) or other drugs. The five-year survival rate is 90%.

Hairy cell leukemia (HCL) is sometimes considered a subset of CLL, but doesn't fit neatly into this pattern. About 80% of affected people are adult men. There are no reported cases in young children. HCL is incurable, but easily treatable. Survival is 96% to 100% at ten years.

Symptoms

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 platelets, which are important in the blood clotting process. This means people with leukemia may become bruised, bleed excessively, or develop pinprick bleeds (petechiae). White blood cells, which are involved in fighting pathogens, may be suppressed or dysfunctional. This could cause the patient's immune system to be unable to fight off a simple infection or to start attacking other body cells.
Finally, the red blood cell deficiency leads to anemia, which may cause dyspnea. All symptoms can be attributed to other diseases; for diagnosis, blood tests and a bone marrow examination are required.
Some other related symptoms:

Fever, chills, night sweats and other flu-like symptoms

Weakness and fatigue

Swollen or bleeding gums

Neurological symptoms (headaches)

Enlarged liver and spleen

Frequent infection

Bone pain

Joint pain

Dizziness

Nausea

Swollen tonsils

Diarrhea

Paleness

Malaise

Unintentional weight loss The word leukemia, which means 'white blood', is derived from the disease's namesake high white blood cell counts that most leukemia patients have before treatment. The high number of white blood cells are apparent when a blood sample is viewed under a microscope. Frequently, these extra white blood cells are immature or dysfunctional. The excessive number of cells can also interfere with the level of other cells, causing a harmful imbalance in the blood count.
Some leukemia patients don't 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 which disrupt the normal production of blood cells. However, the leukemic cells are staying in the marrow instead of entering the bloodstream, where they'd be visible in a blood test. For an aleukemic patient, 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.

Causes and risk factors

There is no single known cause for all of the different types of leukemia. The different leukemias likely have different causes, and very little is certain about what causes them. Researchers have strong suspicions about four possible causes:

natural or artificial ionizing radiation

certain kinds of chemicals

some viruses

genetic predispositions Leukemia, like other cancers, results from somatic mutations in the DNA which activate oncogenes or deactivate tumor suppressor genes, and disrupt the regulation of cell death, differentiation or division. These mutations may occur spontaneously or as a result of exposure to radiation or carcinogenic substances and are likely to be influenced by genetic factors. Cohort and case-control studies have linked exposure to petrochemicals, such as benzene, and hair dyes to the development of some forms of leukemia. Viruses have also been linked to some forms of leukemia. For example, certain cases of ALL are associated with viral infections by either the human immunodeficiency virus or human T-lymphotropic virus (HTLV-1 and -2, causing adult T-cell leukemia/lymphoma). However, a CNN Health report says children may be offered limited protection against leukemia by exposure to certain germs. Fanconi anemia is also a risk factor for developing acute myelogenous leukemia.
Until the cause or causes of leukemia are found, there's no way to prevent the disease. Even when the causes become known, they may not be readily controllable, such as naturally occurring background radiation, and therefore not especially helpful for prevention purposes.

Treatment options for leukemia by type

Acute lymphocytic leukemia (ALL)

Management of ALL focuses on 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). 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 to eliminate any remaining leukemia cells. This typically requires one to three months in adults and four to eight months in children. Patients with low- to average-risk ALL receive therapy with antimetabolite drugs such as methotrexate and 6-mercaptopurine (6-MP). High-risk patients receive higher drug doses of these drugs, plus additional drugs.

CNS prophylaxis (preventive therapy) to stop the cancer from spreading to the brain and nervous system. 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 two years.

Alternatively, allogeneic bone marrow transplantation may be appropriate for high-risk or relapsed patients.

Chronic lymphocytic leukemia (CLL)

Decision to treat
Hematologists base CLL treatment upon both the stage and symptoms of the individual patient. A large group of CLL patients have low-grade disease, which doesn't 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 nodes or spleen

an increase in the rate of lymphocyte production Typical treatment approach
CLL is probably incurable by present treatments. The primary chemotherapeutic plan is 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 immunohemolytic anemia or immune-mediated thrombocytopenia. In resistant cases, single-agent treatments with nucleoside drugs such as fludarabine, pentostatin, or cladribine may be successful. Younger patients may consider allogeneic or autologous bone marrow transplantation.

Acute myelogenous leukemia (AML)

Many different anti-cancer drugs are effective for the treatment of AML. Treatments vary somewhat according to the age of the patient 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.
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 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 chemotherapy with additional drugs. By contrast, maintenance treatment involves drug doses that are lower than those administered during the induction phase.

Chronic myelogenous leukemia (CML)

There are many possible treatments for CML, but the standard of care for newly diagnosed patients is imatinib (Gleevec) therapy. Compared to most anti-cancer drugs, it has relatively few side effects and can be taken orally at home. With this drug, more than 90% of patients will be able to keep the disease in check for at least five years,

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