Leukemia is a form of cancer that affects the body's blood-making system. This includes the lymphatic system and bone marrow. Leukemia is either acute (coming on suddenly) or chronic (lasting a long time). Chronic leukemia rarely affects children; acute leukemia affects adults and children.

Leukemia generally affects one of the two major types of white blood cells. These cells are made in the bone marrow. They circulate throughout the body to help the immune system fight off viruses, infections and other organisms that can invade the body. The two major types of white blood cells are lymphocytes and granulocytes. Leukemias arising from lymphocytes are called lymphocytic or lymphatic leukemias; those from granulocytes are called myelogenous or myelocytic leukemias. Rarer forms are called monocytic leukemias.

Acute lymphocytic leukemia is more likely to arise during childhood. Acute myelocytic leukemia affects adults and children. Chronic myelogenous and chronic lymphocytic leukemia affect mainly adults.

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 area women, and white people get the disease more than other racial or ethnic groups. Adults are 10 times more likely to develop leukemia than are children. Leukemia occurs most often in the elderly. When leukemia occurs in children, it happens most often before age 10.

There are many possible causes of leukemias, including exposure to radiation or to organic chemicals such as benzene and other hydrocarbons. But most of the time no specific cause can be found.

Many agents used to cure or control other types of cancers, including radiation, may, over the course of the person�s life, actually lead to a second cancer, such as leukemia. When a doctor treats a cancer patient, this risk must be considered.

Acute Leukemia
With acute leukemia, immature blood cells reproduce quickly in the bone marrow, where they eventually crowd out healthy cells. When these cells reach high numbers, they can sometimes spread to other organs, causing damage. This is especially true in acute myeloid leukemia. The two main types of acute leukemia involve different types of blood cells:

• Acute lymphocytic leukemia is the most common type of leukemia that affects children, mainly those younger than 10. Adults sometimes develop acute lymphocytic 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 cases 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
Chronic leukemia is when the body produces too many blood cells that are only partially developed 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 lymphocytic 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, abnormal cells in the bone marrow (called lymphocytes) cannot fight infection as well as normal cells can. With chronic lymphocytic leukemia, cancerous cells live in the bone marrow, blood, spleen and lymph nodes, where they cause swelling that appears as swollen glands. People with chronic lymphocytic leukemia can live for long periods, even without any active treatment. Most often, the diagnosis is discovered when a person has a routine blood count that shows an elevation of lymphocytes. Over time, this type of leukemia can require treatment, especially if the person has infections or develops a very high white blood cell count.



• 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.

One of the most exciting advances in chronic myelogenous leukemia has resulted from a better understanding of the Philadelphia chromosome, a defective string of DNA. This genetic defect results in the production of an abnormal protein. There is now a drug that can block the function of this abnormal protein and cause important improvements in blood counts. Sometimes, the drug has led to an apparent disappearance of the abnormal genetic defect. The drug is called imitanib (Gleevec). Imitanib has helped open the doors to increasing our understanding of �targeting� or repairing a specific defect in the cancer cell. This reverts the cancer cell back to near normal state.

Rarer forms of cancer

Lymphatic and myelogenous leukemias are the most common. However, cancers of other types of bone marrow cells can develop. For example, cells that produce platelets (small cells that help in blood clotting) are called megakaryocytes. Leukemia arising from these cells is called megakaryocytic leukemia. The rare form of cancer arising from cells that make red blood cells is called erythroleukemia. Within the most common types of leukemias and in the rare forms of leukemia are sub types. These are based upon specific chemicals on the surface of the leukemic cells.

Most 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 lymphocytic 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:

• Fever
• Fatigue
• Aches in bones or joints
• Headaches
• Skin rashes
• Swollen glands (lymph nodes)
• Frequent infections
• 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 the 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.

The treatment of leukemia is among the most intensive of all cancer therapies. Treatment may severely compromise immune function and the body's infection fighting ability. This is why a substantial amount of supportive care is necessary to help people recover fully. People with leukemia should be treated in medical centers that specialize in the advanced treatments and also offer support to the person during their most vulnerable periods of immune suppression.

Acute Leukemia
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 remission.

With acute lymphocytic leukemia, treatment generally occurs in phases, although not all phases are used for all people with the disease:

• Phase 1 (induction therapy) uses chemotherapy in the hospital to try to control the disease.
• Phase 2 (consolidation) continues chemotherapy, but on an outpatient basis (the person returns to the hospital for treatment, but does not stay overnight) to keep the person in remission.
• Phase 3 (prophylaxis) uses different chemotherapy drugs, sometimes combined with radiation therapy, to prevent the leukemia from entering the brain and central nervous system.
• Phase 4 (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 on 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.

Chronic Leukemia
For chronic lymphocytic leukemia, the next step after diagnosis is to determine the extent of the cancer. This is called staging. There are four stages of chronic lymphocytic 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 lymphocytic 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, the drug 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 person and whether a suitable bone marrow donor is available.

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. If diagnosed with leukemia, consider transferring to a specialized cancer center.

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 lymphocytic leukemia. In general, children with this cancer have a 90% chance of complete remission, with an 80% 5-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 1 month of induction therapy. In some people, however, the disease will return, lowering the cure rate to no more than 40%.



• Chronic lymphocytic 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 3 years after treatment if they have a bone marrow transplant. Only 15% to 25% of those without a transplant live longer than 5 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 and Lymphoma Society
1311 Mamaroneck Ave.
White Plains, NY 10605
Toll-Free: 1-800-955-4572
http://www.leukemia.org

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: 1-800-422-6237
TTY: 1-800-332-8615
E-Mail: cancergovstaff@mail.nih.gov
http://www.nci.nih.gov/

American Cancer Society (ACS)
Toll-Free: 1-800-227-2345
TTY: 1-866-228-4327http://www.cancer.org/

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
E-Mail: nhlbiinfo@rover.nhlbi.nih.gov
http://www.nhlbi.nih.gov/

American Academy of Pediatrics (AAP)
141 Northwest Point Blvd.
Elk Grove Village, IL 60007-1098
Phone: 847-434-4000
Fax: 847-434-8000
E-Mail: kidsdocs@aap.org
http://www.aap.org/

National Institute of Child Health and Human Development
P.O. Box 3006
Rockville, MD 20847
Toll-Free: 1-800-370-2943
TTY: 1-888-320-6942
E-Mail: nichdinformationresourcecenter@mail.nih.gov
http://www.nichd.nih.gov/