ALL affects roughly 6,000 people every year and is most common in children under the age of 10. In adults the average age of diagnosis is 65.

Lymphocytes evolve from immature stem cells that grow into T lymphocytes (T cells), B lymphocytes (B cells), or natural killer (NK) cells. Each plays a special role in the body’s immune defense.

In acute lymphocytic leukemia (ALL) the DNA or blueprint of the blood cells is damaged, and they never grow up to function as normal, infection-fighting cells. Instead they become stuck at an earlier stage of development called blasts. The blasts begin growing rapidly and eventually crowd out the production of normal red and white blood cells and platelets in the bone marrow.
As the number of oxygen-carrying red blood cells decline, patients may develop anemia, appearing pale, tired or short of breath. A decline in platelets that normally help the blood clot may lead to easy bruising or bleeding. A decline in white blood cells puts patients at increased risk for infections that can be life threatening.

Since ALL is a cancer of the blood and bone marrow it may also be found in the other organs including the liver, spleen, lymph nodes, and skin

Acute lymphocytic leukemia does not appear to be inherited disease. However, there are some diseases involving genetic changes that seem to increase a person’s risk of developing ALL. These include:

• Down syndrome
• Klinefelter syndrome
• Fanconi anemia
• Bloom syndrome
• Ataxia-telangiectasia
• Neurofibromatosis

Children with ALL respond better to treatment than adults for a variety of reasons: their cells are still maturing, the disease appears differently in this age group, and they can often handle aggressive treatment better than adults.