Acute lymphocytic leukemia is a type of cancer that affects the white blood cells, causing rapid production of abnormal lymphocytes. In medical terms, this leukemia is also known as acute lymphoblastic leukemia (ALL). Other synonyms for acute lymphocytic leukemia include childhood acute lymphoblastic leukemia, precursor B-cell lymphoblastic leukemia/lymphoma, and precursor T-cell lymphoblastic leukemia/lymphoma. ALL is the most common type of cancer in children, accounting for about 80% of cases, with an incidence of about 1 in 3,500 children under the age of 15. Treatment for acute lymphocytic leukemia typically involves chemotherapy, radiation therapy, or a stem cell transplant.