LEUKEMIA IS THE TERM USED to describe cancer of the bone marrow. This spongy material fills the bones in the body and produces blood cells. In a child with chronic myelogenous leukemia (CML), the bone marrow creates millions of cancerous white blood cells (WBCs). As the bone marrow becomes packed with these abnormal cells, they crowd out the healthy cells and symptoms of CML begin to develop.

CML is rare in children, accounting for less than 3% of all childhood leukemias. It is most often diagnosed in adolescents and is rarely found in children younger than age 6. This chapter describes CML and covers risk factors, signs and symptoms, diagnosis, prognosis, and treatment.