Acute lymphoblastic leukemia (ALL) is the most common form of childhood cancer. It affects lymphocytes, a class of white blood cells. Leukemic cells accumulate in the bone marrow, replace normal blood cells and spread to the liver, spleen, lymph nodes, central nervous system, kidneys and gonads.
This cancer affects about 2,000 children each year in the United States and usually occurs between the ages of three and five.
Close to 98 percent of children with newly-diagnosed ALL attain complete remission (absence of leukemic cells) in four to six weeks. With modern therapy, 70 to 75 percent of children may be cured. If a child does not relapse within three years after therapy is complete, the likelihood of a relapse never recurring is excellent.