Definition of Acute lymphocytic leukemia (ALL):

Acute lymphocytic leukemia (ALL) is a fast-growing cancer in which the body produces a large number of immature white blood cells (lymphocytes). These cells can be found in the blood, bone marrow, lymph nodes, spleen, and other organs.

Causes, incidence, and risk factors:

ALL makes up 80% of childhood acute leukemias. Most cases occur in children ages 3 - 7. The disease may also occur in adults.

In acute leukemia, cancerous cells multiply quickly and replace normal cells. Cancerous cells take over normal parts of bone marrow, causing bone marrow failure. A person with ALL is more likely to bleed and have infections because there are fewer normal blood cells.

Most cases of ALL have no obvious cause. However, chromosome problems, radiation, toxins such as benzene, and some chemotherapy drugs may play a role in the development of leukemia.

Persons with Down syndrome or who have a brother or sister with leukemia have an increased risk for ALL.