What Is Leukemia?

Leukemia is cancer of the blood cells—usually the white blood cells—and develops in the bone marrow. Leukemic cells look different than normal cells and do not function properly.

The bone marrow is the soft, spongy center of the long bones that produces the three major blood cells:

• White blood cells to fight infection
• Red blood cells that carry oxygen
• Platelets that help with blood clotting and stop bleeding

Leukemia is the most common form of cancer in childhood. It affects approximately 3,000 children each year in the United States, accounting for about 30% of childhood cancers. Learn about the childhood leukemia treatments offered at Lucile Packard Children's Hospital Stanford.