What Is It?
Leukemia is a form of cancer that affects the body's blood-making system, including the lymphatic system and bone marrow. Leukemia is either acute (coming on suddenly) or chronic (lasting a long time). Chronic leukemia rarely affects children, whereas acute leukemia affects both adults and children.
Leukemia accounts for about 2% of all cancers. It strikes 9 out of every 100,000 people in the United States every year. Men are more likely to develop leukemia than women, and white people get the disease more than other racial or ethnic groups. Adults are 10 times more likely to develop leukemia than children. Leukemia occurs most often in the elderly. When leukemia occurs in children, it happens most often before age 4.
With acute leukemia, immature blood cells reproduce quickly in the bone marrow, where they eventually crowd out healthy cells. When present in high numbers, these immature, abnormal cells sometimes can spread to other organs, causing damage, especially in a type of leukemia called acute myeloid leukemia. The two main types of acute leukemia involve different types of blood cells:
Acute lymphoid leukemia is the most common type of leukemia that affects children, mainly those younger than 10. Adults sometimes develop acute lymphoid leukemia, but it is rare in people older than 50. It occurs when primitive blood-forming cells called lymphoblasts reproduce without developing into normal blood cells. These abnormal cells crowd out healthy blood cells. They can collect in the lymph nodes and cause swelling.
Acute myeloid leukemia accounts for 50% of leukemia diagnosed in teenagers and in people in their 20s. It is the most common acute leukemia in adults. It occurs when primitive blood-forming cells called myeloblasts reproduce without developing into normal blood cells. Immature myeloblast cells crowd the bone marrow and interfere with the production of healthy normal blood cells. This leads to anemia (not having enough red blood cells), bleeding and bruising (due to a lack of blood platelets, which help the blood to clot), and frequent infections because there are not enough protective white blood cells.
Chronic leukemia is when the body produces too many blood cells that have developed part way but often cannot function like mature blood cells. Chronic leukemia usually develops more slowly and is a less dramatic illness than acute leukemia. There are two main types of chronic leukemia:
Chronic lymphoid leukemia is rare in people younger than 30. It is more likely to develop the older a person gets. The greatest number of cases occur in people between ages 60 and 70. In this form of leukemia, the abnormal cells in the bone marrow are a type of blood cell called lymphocytes. These abnormal cells cannot fight infection as well as normal cells can. With chronic lymphoid leukemia, cancerous cells live in the bone marrow, blood, spleen and lymph nodes, where they cause swelling that appears as swollen glands.
Chronic myeloid leukemia occurs most often in people between ages 25 and 60. In this form of leukemia, the abnormal cells are a type of blood cell called myeloid cells. Chronic myeloid leukemia cells usually involve an abnormality in the genetic code called the Philadelphia chromosome. However, this disease is not an inherited defect. Chronic myeloid leukemia sometimes can be cured with a bone marrow transplant.
The vast majority of leukemias occur in people without any family history of leukemia and are not believed to be inherited. However, some forms of the disease, especially chronic lymphoid leukemia, occasionally strike close relatives in the same family. Certain genetic abnormalities (such as Down syndrome) have been linked to the development of specific forms of leukemia. In cases of myeloid leukemia, an increased risk of the illness has been linked to excessive exposure to radiation and to heavy exposure to benzene, a chemical found in unleaded gasoline.
Early symptoms of leukemia are like symptoms of the flu or other common diseases. Symptoms include:
Aches in bones or joints
Swollen glands (lymph nodes)
Unexplained weight loss
Bleeding or swelling of gums
An enlarged spleen or liver, or a feeling of abdominal fullness
Slow-healing cuts, nosebleeds or frequent bruises
Your doctor may not suspect leukemia based on your symptoms alone. However, during your physical examination, your doctor may discover that you have swollen lymph nodes or an enlarged liver or spleen. The diagnosis may become clearer when routine blood tests (especially blood cell counts) show abnormal results. Other tests will be done, including a bone marrow biopsy (a sample of bone marrow is removed and examined), more blood tests to detect the presence of abnormal cells and, sometimes, tests for genetic abnormalities, such as the Philadelphia chromosome.
In general, chronic leukemia progresses more slowly than acute leukemia. Without a relatively new drug imatinib (Gleevec) or a bone marrow transplant, people with chronic myeloid leukemia typically have several years of stability before developing a picture more like acute myeloid leukemia. Whether imatinib can delay or prevent the transformation from a chronic leukemia to an acute leukemia remains to be seen.
There is no way to prevent most forms of leukemia. In the future, genetic testing may play a larger role in identifying people who are more likely to develop the illness. Until then, close relatives of people with leukemia should undergo routine physical exams, unless suspicious symptoms develop.
Unlike other cancers, the treatment of acute leukemia does not depend on how far the disease has advanced but on the person's condition and on whether the person is newly diagnosed, continuing treatment or in remission (the disease is controlled) or the disease has come back after a remission.
With acute lymphoid leukemia, treatment generally occurs in phases, although not all phases are used for all people with the disease:
Phase 1 (called induction therapy) uses chemotherapy in the hospital to try to control the disease.
Phase 2 (called consolidation) continues chemotherapy, but on an outpatient basis (returning to the hospital for treatment, but not staying overnight) to keep the person in remission.
Phase 3 (called prophylaxis) uses different chemotherapy drugs, sometimes combined with radiation therapy, to prevent the leukemia from entering the brain and central nervous system.
Phase 4 (called maintenance) involves regular physical exams and laboratory tests after the leukemia has been treated to be sure that it has not returned.
Recurrent leukemia uses different doses of various chemotherapy drugs to combat a disease that has returned. People may need several years of chemotherapy to keep the leukemia in remission. Some people may receive a bone marrow transplant.
With acute myeloid leukemia, treatment generally depends on the type of the disease, as well as the person's age and overall health. Usually people receive induction therapy in an effort to send the leukemia into remission. Consolidation therapy also is used. For all types of acute leukemia, a bone marrow transplant is an option when chemotherapy alone has been less successful.
For chronic lymphoid leukemia, the next step after diagnosis is to determine the extent of the cancer. This is called staging. There are four stages of chronic lymphoid leukemia:
Stage 0 There are too many lymphocytes in the blood. Generally, there are no other symptoms of leukemia.
Stage I Lymph nodes are swollen because of too many lymphocytes in the blood.
Stage II Lymph nodes, spleen and liver are swollen as a result of an overabundance of lymphocytes.
Stage III Anemia has developed because there are too few red blood cells in the blood.
Stage IV There are too few platelets in the blood. Lymph nodes, spleen and liver may be swollen. Anemia may be present.
Treatment of chronic lymphoid leukemia depends on the stage of the disease, as well as on the person's age and overall health. In the earliest stage, treatment may not be needed, although the person's health will be monitored closely. In Stage I or II, observation or chemotherapy is the usual treatment. In Stage III or IV, intensive chemotherapy or multiple-drug chemotherapy may be used. Some people also may be treated with a bone marrow transplant.
For chronic myelogenous leukemia, a drug called imatinib has become standard therapy, especially for those in the early stage of this disease. Whether a bone marrow transplant also is done depends on the stage of the disease, the health of the patient, and whether a suitable bone marrow donor is available.
When To Call A Professional
Call your doctor if you have frequent infections, abnormal bruising or bleeding, swollen glands, unexplained weight loss, persistent fatigue or any other symptoms of leukemia.
Overall, about 42% of people with leukemia live for at least five years after they are diagnosed. However, the survival rate varies a lot among the different types of leukemia:
Acute lymphoid leukemia In general, children with this cancer have a 90% chance of complete remission, with an 80% five-year survival rate. The adult prognosis is not as good, with only 25% to 35% of adults surviving for five years.
Acute myeloid leukemia With proper treatment, 70% to 75% of people with this cancer can expect to go into remission. About 80% who go into remission will do so within one month of induction therapy. In some people, however, the disease will return, lowering the cure rate to no more than 40%.
Chronic lymphoid leukemia On average, people with this cancer survive 9 years, although some have survived as long as 35 years. In Stage I or II, remission occurs in about 70% of people treated with chemotherapy, although the cancer always comes back eventually.
Chronic myeloid leukemia How long people with chronic myeloid leukemia survive depends on the age of the person, the extent of the disease and the treatments used. For example, 60% of people younger than 40 with mild symptoms survive three years after treatment if they have a bone marrow transplant. Only 15% to 25% of those without a transplant live longer than five years. A few people have lived as long as 20 years. Even the few years of experience with imatinib suggest that the drug will improve survival rates. However, how much the drug helps won't be known for some time.
The Leukemia & Lymphoma Society
1311 Mamaroneck Ave.
White Plains, NY 10605
Phone: (914) 949-5213
Toll-Free: (800) 955-4572
Fax: (914) 949-6691
National Cancer Institute (NCI)
U.S. National Institutes of Health
Public Inquiries Office
Building 31, Room 10A03
31 Center Drive, MSC 8322
Bethesda, MD 20892-2580
Phone: (301) 435-3848
Toll-Free: (800) 422-6237
TTY: (800) 332-8615
American Cancer Society (ACS)
1599 Clifton Road, NE
Atlanta, GA 30329-4251
Toll-Free: (800) 227-2345
National Heart, Lung, and Blood Institute (NHLBI)
P.O. Box 30105
Bethesda, MD 20824-0105
Phone: (301) 592-8573
TTY: (240) 629-3255
Fax: (301) 592-8563
American Academy of Pediatrics (AAP)
141 Northwest Point Blvd.
Elk Grove Village, IL 60007-1098
Phone: (847) 434-4000
Fax: (847) 434-8000
National Institute of Child Health & Human Development
Building 31, Room 2A32
31 Center Drive
Bethesda, MD 20892-2425
Toll-Free: (800) 370-2943Fax: (301) 496-7101
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