Acute lymphoblastic leukemia (ALL)

ALL is the most common form of childhood cancer. It affects lymphocytes, a type of white blood cells. Leukemic cells accumulate in the bone marrow, replace normal blood cells and spread to other organs including the liver, spleen, lymph nodes, central nervous system, kidneys and gonads. In the United States, about 3,000 children each year are found to have acute lymphoblastic leukemia. Peak incidence occurs from 3 to 5 years of age.

ALL affects slightly more boys than girls. It occurs more frequently among whites than blacks. Although siblings of leukemic children have a slightly higher risk of developing the disease, the incidence is relatively low.

About 98 to 99 percent of children with newly diagnosed ALL attain initial complete remissions (absence of detectable leukemic cells by microscopic examination) in four to six weeks. About 80 percent of children can be cured. Patients who remain leukemia-free for 10 years or more can be considered cured.

Chemotherapy is used to kill leukemia cells. All chemotherapy is stopped after two to three years of treatment.