Chronic myeloid leukemia (CML) is a blood cancer that develops in the bone marrow, where blood cells are made. In CML, abnormal white blood cells grow uncontrollably, interfering with normal blood cell production. The condition is considered "chronic" because the leukemia cells typically grow more slowly than in acute Show Full Answer
Chronic myeloid leukemia (CML) is a blood cancer that develops in the bone marrow, where blood cells are made. In CML, abnormal white blood cells grow uncontrollably, interfering with normal blood cell production. The condition is considered "chronic" because the leukemia cells typically grow more slowly than in acute forms, which means symptoms may not appear for some time.
CML affects the myeloid cells, which normally develop into red blood cells, certain white blood cells, and platelets. The disease is characterized by the presence of the Philadelphia chromosome, which occurs when pieces of chromosomes 9 and 22 switch places. This creates a fusion gene called BCR-ABL that produces a protein causing cells to grow and divide uncontrollably. CML progresses through three phases. Most people are diagnosed in the chronic phase. As the disease moves into the accelerated phase, the number of immature white blood cells (called blasts) increases. The condition can eventually progress to a blast phase, where it may be classified as acute myeloid leukemia (AML).
CML most commonly affects older adults, with nearly half of all diagnoses occurring in people age 65 or older. Approximately 9,000 new cases are diagnosed annually in the United States, representing about 15% of all leukemia cases.
March 25, 2025