Leukemia

Leukemia starts in the soft, inner part of the bones (bone marrow), but often moves quickly into the blood. It can then spread to other parts of the body, such as the lymph nodes, spleen, liver, central nervous system and other organs. Both children and adults can get leukemia, which is a complex disease with many different types and subtypes.

Bone marrow is the soft, spongy, inner part of bones. All of the different types of blood cells are made in the bone marrow. Bone marrow includes blood-forming cells, fat cells and tissues that aid the growth of blood cells. Early blood cells are called stem cells which grow in an orderly process to produce red blood cells, white blood cells and platelets. There are three main types of white blood cells - granulocytes, monocytes and lymphocytes.

Any of the blood-forming or lymphoid cells can turn into a leukemic cell. Once that happens, the cell reproduces to form many new cancer cells. Eventually, these cells can overwhelm the bone marrow, spill out into the bloodstream and spread to other organs.

There are four common types of leukemia based on how quickly the disease develops and the type of white blood cell that is affected. In acute leukemia blood cells are very abnormal, increase rapidly and worsen quickly. In chronic leukemia the abnormal blood cells can still do their work early in the disease but slowly get worse.

Chronic Lymphocytic Leukemia (most often occurs in those older than age 55 and almost never in children);
Chronic Myeloid Leukemia (affects mainly adults);
Acute Lymphocytic Leukemia (most common type of leukemia in young children but also may affect adults); and
Acute Myeloid Leukemia (occurs in both adults and children).

Facts: According to the Illinois State Cancer Registry, in 2008, about 1,720 new cases of leukemia will be diagnosed in Illinois. Of these, about 950 will be in men and about 770 will be in women. About 1000 Illinoisans will die of leukemia in 2008.

The exact cause of leukemia is not known. Studies have found the following risk factors for leukemia.

Radiation: People exposed to very high levels of radiation are much more likely to develop leukemia. These high levels of radiation may have been caused by atomic bomb explosions, nuclear power plant accidents and medical treatment using radiation.
Exposure to chemicals: Exposure to high levels of chemicals in the work place, including benzene and formaldehyde, can cause leukemia.
Smoking: Smoking is a proven risk factor for acute myeloid leukemia.
Drugs: Drugs with alkylating agents, commonly used in chemotherapy, are associated with the development of leukemia after long-term therapy.
Genetic disorders: Certain genetic disorders like Down syndrome may increase the risk of developing leukemia.

Depending on the number of abnormal cells and where these cells collect, patients with leukemia may have a number of symptoms.

• fever or night sweats
• frequent infections
• feeling weak or tired
• headache
• bleeding and bruising easily (bleeding gums, purplish patches in the skin or tiny red spots under the skin)
• pain in the bones or joints
• swelling or discomfort in the abdomen
• swollen lymph nodes, especially in the neck or armpit
• unintentional weight loss

An infection or another problem also could cause these symptoms. It is important to report any of these symptoms to a doctor.

Most people who develop leukemia do not have any of the risk factors. The cause of leukemia is unknown. Therefore, preventing most cases of leukemia is not possible. There is one important exception: smoking. About 20 percent of adult acute myeloid leukemia cases are linked to smoking.

• American Cancer Society
• Leukemia and Lymphoma Society
• National Cancer Institute