Leukemia

Conditions and Treatments

The majority of childhood leukemias are acquired genetic diseases, meaning that gene mutations and chromosome abnormalities in cells occur sporadically or by chance.

The immune system plays an important role in protecting the body from diseases, and possibly cancer. An alteration or defect in the immune system may increase the risk for developing leukemia. Factors such as exposure to certain viruses, environmental factors, chemical exposures and various infections have been associated with damage to the immune system. But little is known about the causes of childhood leukemia, with the exception of specific genetic syndromes.

The reproduction of normal, healthy cells is controlled by signals sent by the body to indicate when cell reproduction should begin and stop. When leukemia occurs, white cells in bone marrow - the spongy tissue inside the large bones -- don't respond to these signals and reproduce abnormal cells, regardless of the space available. These abnormal blood cells reproduce very quickly and don't function as healthy white blood cells to fight infection. These immature blood cells, called blasts, crowd out healthy cells in bone marrow, causing symptoms such as infections, anemia and bleeding.

In a form of leukemia called myelodysplastic syndromes or "pre-leukemia," the body produces defective white cells as well as defective red cells and platelets.

Reviewed by health care specialists at UCSF Children's Hospital.
Last updated May 8, 2007