Leukemia



Leukemias are cancers of the blood-forming tissues. White blood cells may be produced in excessive amounts and are unable to work properly which weakens the immune system.

The blood is made up of fluid called plasma and three types of cells and each type has special functions. White blood cells (also called WBCs or leukocytes) help the body fight infections and other diseases. Red blood cells (also called RBCs or erythrocytes) carry oxygen from the lungs to the body's tissues and take carbon dioxide from the tissues back to the lungs. The red blood cells give blood its color. Platelets (also called thrombocytes) help form blood clots that control bleeding.

Blood cells are formed in the bone marrow, the soft, spongy center of bones. New (immature) blood cells are called blasts. Some blasts stay in the marrow to mature. Some travel to other parts of the body to mature.

Normally, blood cells are produced in an orderly, controlled way, as the body needs them. This process helps keep us healthy. When leukemia develops, the body produces large numbers of abnormal blood cells. In most types of leukemia, the abnormal cells are white blood cells. The leukemia cells usually look different from normal blood cells, and they do not function properly.

Each year, leukemia is diagnosed in about 29,000 adults and 2,000 children in the United States.

In both men and women, leukemia incidence is highest among whites and lowest among Chinese, Japanese, and Koreans. The incidence in men is about 50% higher than in women for all racial/ethnic groups except Vietnamese, among whom the male rates are only slightly higher. Ethnic differences in the incidence rates are small in the youngest adult age group (30-54 years), but become more evident in each of the older age groups. It is found that childhood leukemia rates are highest among Filipinos, followed by white Hispanics, non-Hispanic whites and blacks.

Treatment
Treatment strategies vary by category (ALL, AML, CLL, CML). Successful treatment consists of ablation of leukemia in the bone marrow and treatment or prevention of systemic disease, including infiltration of visceral sites.

CLL usually has a protracted, indolent course, and therefore is treated conservatively (treatment is deferred until the patient becomes symptomatic).

Splenectomy or splenic radiation is a consideration for splenomegaly due to infiltration by CLL.

Key words
Prophylaxis (prophylactic)--administration of treatment in the absence of clinical symptoms to prevent the worsening of the condition; for example prophylactic CNS radiation to prevent CNS involvement, antibiotic prophylaxis to prevent infection Sanctuary-site disease--leukemia cells present in visceral organs, such as brain, central nervous system, or testes

Surgery
Cancer-directed surgery is generally not performed for the treatment of leukemia. Surgery for leukemia is included with surgical treatment for “all other sites.”

Radiation Therapy
Radiation therapy to the central nervous system is prophylactic treatment to prevent or delay the occurrence of metastases from some varieties of leukemia. CNS radiation is not indicated for AML, but is important for ALL.

Involvement of single lymph node chains with CLL can be treated with radiation therapy.