Overview Chronic myelogenous leukemia (CML) is an uncommon type of leukemia. It is a slow-growing cancer in which the bone marrow makes too many white blood cells. Understanding Your Diagnosis Your CML may have been discovered during a routine blood test. About half of all people with CML do not have symptoms at the time the disease is diagnosed. Deciding on Treatment Treatment for CML is usually systemic, meaning that the treatment kills or controls cancer cells throughout the body. Chemotherapy is one type of systemic treatment.