Acute lymphocytic leukemia (ALL) is a form of leukemia, or cancer of the body’s blood-forming cells. It is the most common form of leukemia in children, according to the American Cancer Society (ACS).

Also known as acute lymphoblastic leukemia, ALL affects the body’s blood making system, including bone marrow and the lymphatic system. ALL develops from lymphoblasts (a type of white blood cell) in the bone marrow. Bone marrow is the soft, inner component of bones, where white blood cells, red blood cells and platelets are formed.

In patients with ALL, the bone marrow manufactures a large number of abnormal white blood cells. Over time they increase, crowding out normal white blood cells, red blood cells and platelets. This results in anemia, bleeding disorders and a decreased ability to fight off infection.

ALL develops in the bone marrow but typically spreads quickly into the blood. Eventually it spreads further into the lymph nodes, the liver, the spleen, the brain, the spinal cord and the testicles. Without successful treatment, the disease is usually fatal.

The exact cause of ALL has not been identified. Researchers have gained a greater understanding of how specific changes in DNA can cause cells to develop into leukemia. In most cases of leukemia, the DNA chanes are acquired, occurring after birth, rather than inherited. A number of risk factors have also been identified, including age and exposure to high levels of radiation. 

Symptoms of ALL vary depending on where it has spread in the body. General signs and symptoms include weight loss, fever, loss of appetite and weakness.

ALL may be first diagnosed in routine blood tests. However, additional tests typically are necessary to examine blood and bone marrow cells. Diagnostic tests for ALL may include bone marrow tests and lumbar puncture. The treatment and prognosis for ALL depends on the subtype of the disease, as well as certain additional factors including the patient’s age. It may include chemotherapy, radiation therapy, and bone marrow/stem cell transplantation. ALL patients usually receive a combination of these therapies.

The ACS predicts that in 2007 there will be approximately 5,200 new cases of ALL in the United States. The disease is more common in children, with only 20 percent of cases occurring in adults. ALL is slightly more common in males than in females.

According to the Leukemia & Lymphoma Society, from 1995 to 2001, the five-year survival rate for acute lymphocytic leukemia was 65 percent. In 2007, the five-year survival rate in children 15 years old and younger increased to 87 percent. The improved survival rate is largely due to advances in treatment of the disease.