What Is It?

Leukemia is a form of cancer that affects your 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, while acute leukemia affects both adults and children.

Leukemia accounts for about 2 percent of all cancers. It strikes nine out of every 100,000 people in the United States every year. Men are more likely to develop leukemia than women, and whites get the disease more than other racial or ethnic groups. Adults are 10 times more likely to develop leukemia than children, and it occurs most often in the elderly. When leukemia occurs in children, it happens most often before age 4.

Acute leukemia
In acute leukemia, immature blood cells reproduce quickly in the bone marrow, where they eventually crowd out healthy cells. These immature, abnormal cells also can spread to other organs, leading to damage. 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, primarily those under 10. Adults sometimes develop acute lymphoid leukemia, but it is rare in people over age 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 percent of leukemia diagnosed in teen-agers and people in their 20s, and 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 enough red blood cells) and frequent infections because there are not enough protective white blood cells.

Chronic leukemia
Chronic leukemia is when your body produces too many blood cells that have developed part way, but that 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 under 30, but is more likely to develop the older a person gets. The greatest number of cases occur in people between the ages of 60 and 70. In this form of leukemia, the abnormal cells in the bone marrow are a type of blood cells called lymphocytes. These abnormal cells cannot fight infection as well as normal cells can. In chronic lymphoid leukemia, cancerous cells live in the bone marrow, blood, spleen and lymph nodes, where they produce 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 cells called myeloid cells. Chronic myeloid leukemia cells usually involve a genetic (inherited) abnormality called the Philadelphia chromosome. However, this disease is not always inherited. People who are exposed to too much radiation or benzene, a chemical found in unleaded gasoline, are more likely to develop this form of leukemia. 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) also 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. Diagnostic procedures will follow, including a bone-marrow biopsy (a sample of bone marrow is removed and examined), specialized 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 Gleevec, a relatively new drug, or a bone-marrow transplant, patients with chronic myeloid leukemia typically have several years of stability before developing a picture more like acute myeloid leukemia. Whether the transformation from a chronic leukemia to an acute leukemia can be delayed or prevented by Gleevec 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 follow a normal schedule of routine physical exams, unless suspicious symptoms develop.

Acute leukemia
Unlike other cancers, the treatment of acute leukemia does not depend on how far the disease has advanced, but on the patient’s condition and on whether the patient is newly diagnosed, continuing treatment, in remission (the disease is controlled) or the disease has come back after a remission.

In acute lymphoid leukemia, treatment generally occurs in phases, although not all phases are used for all patients:

• 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 patient 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 further doses of various chemotherapy drugs in different dosages to combat a disease that has returned. Patients may need several years of chemotherapy to keep the leukemia in remission. Some patients may receive a bone-marrow transplant.

In acute myeloid leukemia, treatment generally depends on the type of the disease, as well as the patient’s age and overall health. Usually patients receive induction therapy in an effort to send the leukemia into remission. Consolidation and maintenance therapies also may be used, but they are less effective for acute myeloid leukemia than for acute lymphoid leukemia. For all types of acute leukemia, a bone-marrow transplant is an option when chemotherapy alone has been less successful.

Chronic leukemia
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 will depend on the stage of the disease, as well as the patient’s age and overall health. In the earliest stage, Stage 0, treatment may not be needed, and the patient’s health will be monitored closely. In Stage I or II, either observation or chemotherapy is the usual treatment. In Stage III or IV, more intensive or multiple-drug chemotherapies may be used. Some patients also may be treated with a bone-marrow transplant.

A relatively new drug called Gleevec has become standard therapy for patients in the early stage of this disease, with or without bone-marrow transplantation.

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 percent of people with leukemia live for at least five years after diagnosis. However, the survival rate varies a lot among the different types of leukemia:

• Acute lymphoid leukemia — In general, children with this type of cancer have a 90-percent chance of obtaining a complete remission, with an 80-percent, five-year survival rate. The adult prognosis is not as good, with only 25 percent to 35 percent of adult patients surviving for five years.
• Acute myeloid leukemia — With proper treatment, 70 percent to 75 percent of people with this type of cancer can expect to go into remission. About 80 percent of patients who go into remission will do so within one month of induction therapy. In some of these patients, however, the disease will return, lowering the cure rate to no more than 40 percent
• Chronic lymphoid leukemia — On average, patients with this cancer survive nine years, although some patients have survived as long as 35 years. In Stage I or II, remission occurs in about 70 percent of patients treated with chemotherapy, although the cancer always comes back eventually.
• Chronic myeloid leukemia — How long patients with chronic myeloid leukemia survive depends on the age of the patient, the extent of the disease, and the treatments used. For example, 60 percent of patients under age 40 with mild symptoms survive three years after treatment with bone-marrow transplantation. However, only 15 percent to 25 percent of patients without a transplant live longer than five years. A few patients have lived as long as 20 years. It’s possible the new drug, Gleevec, will improve survival rates, but that won’t be known for a few years.

Diseases and Conditions Center

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.