Leukemia is a cancer of the blood cells. It is the most common type of blood cancer and affects 0 times as many adults as children. Most people diagnosed with leukemia are over 50 years old.
Leukemia Starts in Bone Marrow
Leukemia usually begins in the bone marrow, the soft material in the center of most bones where blood cells are formed. The bone marrow makes three types of blood cells, and each type has a special function.
- White blood cells fight infection and disease.
- Red blood cells carry oxygen throughout the body.
- Platelets help control bleeding by forming blood clots.
In people with leukemia, the bone marrow produces abnormal white blood cells, called leukemia cells. At first, leukemia cells function almost normally. But over time, as more leukemia cells are produced, they may crowd out the healthy white blood cells, red blood cells, and platelets. This makes it difficult for the blood to carry out its normal functions.
The main types of Leukemia are :-
- Acute lymphoblastic 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.
- 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. 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.
- 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 diagnosis of leukemia is based on a complete medical history and physical examination and on the following diagnostic tests:
- Complete blood count (CBC)
- Bone marrow aspirate and biopsy
- Lumbar puncture (spinal tap)
- Chest x-ray
Blood tests may be done to evaluate the liver and kidneys and how the blood is clotting, and to conduct genetic studies. Blood may be removed from a vein with a needle or a central venous line. When a central venous line is used, a plastic tube or catheter is inserted into a large vein in the chest, neck or arm. This is also a common way to give chemotherapy. The use of a central line prevents a lot of needle sticks.
Bone marrow aspirates and biopsies involve inserting a needle into a bone in the pelvis or spine and removing about 2 teaspoons of marrow for examination. Bone marrow studies require pain medicine and usually sedation or general anesthesia.
Spinal taps involve inserting a needle into the lower back, between the bones of the spinal column or backbone, to remove the fluid that surrounds the brain and spinal cord. The same needle can be used to insert medicines to prevent or treat leukemia in the brain or spinal cord (intrathecal chemotherapy).
Chest x-rays are taken to see if there is a mass of cells in the thymus that may affect breathing.
Most forms of leukemia are treated with pharmaceutical medications, typically combined into a multi-drug chemotherapy regimen. Some are also treated with radiation therapy. In some cases, a bone marrow transplant is useful.
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. 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 in high-risk patients.
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 patients.
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). While generally considered incurable, CLL progresses slowly in most cases. Many people with CLL lead normal and active lives for many years-in some cases for decades. Because of its slow onset, early-stage CLL is, in general, not treated since it is believed that early CLL intervention does not improve survival time or quality of life. Instead, the condition is monitored over time to detect any change in the disease pattern.
The decision to start CLL treatment is taken when the patient's clinical symptoms or blood counts indicate that the disease has progressed to a point where it may affect the patient's quality of life. Combination chemotherapy regimens are effective in both newly-diagnosed and relapsed CLL. Combinations of fludarabine with alkylating agents (cyclophosphamide) produce higher response rates and a longer progression-free survival than single agents: FC (fludarabine with cyclophosphamide); FR (fludarabine with rituximab); FCR (fludarabine, cyclophosphamide, and rituximab); CHOP (cyclophosphamide, doxorubicin, vincristine and prednisolone).
Monoclonal antibodies, such as alemtuzumab (directed against CD52), rituximab (directed against CD20), and ofatumumab (Arzerra ) (directed against CD20) are also used.
Stem cell transplantation
Younger patients that are at high risk for dying from CLL might consider hematopoietic stem cell transplantation (HSCT). Autologous stem cell transplantation, a lower-risk form of treatment using the patient's own blood cells, is not curative. Myeloablative (bone marrow killing) forms of allogeneic stem cell transplantation, a high-risk treatment using blood cells from a healthy donor, may be curative for some patients, but most patients cannot tolerate the treatment. An intermediate level, called reduced-intensity conditioning allogeneic stem cell transplantation, may be better tolerated by older or frail patients.
Many different anti-cancer drugs are effective for the treatment 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.
There are many possible treatments for CML, but the standard of care for newly diagnosed patients is imatinib therapy. In a more advanced, uncontrolled state, when the patient cannot tolerate imatinib, or if the patient 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.