What Is Acute Lymphocytic Leukemia?

This content has been reviewed and approved by

Hagop M. Kantarjian, MD
Chairman & Professor, Leukemia Department
MD Anderson Cancer Center
University of Texas

Leukemia is cancer of the blood cells, usually the white blood cells. Acute lymphocytic leukemia (ALL) occurs when bone marrow and the lymph system produce too many lymphocytes. A lymphocyte is a type of white blood cell that fights infection by making antibodies that attack harmful organisms.

About 5,430 people in the United States will be diagnosed with ALL in 2008, according to the American Cancer Society. Although ALL is the most common leukemia in children, approximately one-third of cases occur in adults.

A person with ALL has immature lymphocytes that cannot function properly. They crowd out other blood cells and may collect in blood, bone marrow, and lymph tissue. People with ALL have difficulty in fighting infection. They also have a low platelet count and may have bleeding problems. They also do not produce hemoglobin or red cells (that carry oxygen), so they may have anemia and feel tired.

The word "acute" means sudden or rapid in onset. Acute leukemia can occur in a short period of days or weeks. Chromosome (DNA) abnormalities (extra chromosomes and structural changes in the chromosome material) are present in the majority of patients with ALL.