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What is Chronic Myeloid Leukemia (CML)?

Leukemia is cancer of the bone marrow, which is the organ responsible for blood cell development.

Normally, there are three types of cells in your blood stream:

  • White blood cells
  • Red blood cells
  • Platelets

Bone marrow is the soft, inner part of the bones and is made up of blood stems cells and tissues that support bone growth.

In patients with leukemia, immature cells called "blasts" overtake their healthy bone marrow. In the normal state, blasts are very rare, and divide and become mature white blood cells, red blood cells, and platelets.

Chronic myeloid leukemia is classified as a myeloproliferative neoplasm. These are slow growing leukemias which result in overproduction of white blood cells by the bone marrow, causing high blood counts.

In CML, patients have an abnormal chromosome in their blood cells called the Philadelphia chromosome. No one is born with the Philadelphia chromosome; rather it is a result of a genetic accident that happens in a blood-forming stem cell in the bone marrow.

The Philadelphia chromosome was first discovered at the University of Pennsylvania. It is actually a combination of 2 chromosomes (chromosomes 9 and 22) that become abnormally fused. This fusion results in the creation of a new gene called BCR-ABL.

Acute vs. Chronic Myeloid Leukemia

Unlike acute myeloid leukemia (AML), CML takes longer to develop. Most people can live with CML for many years. Rarely CML can also turn into acute leukemia, which needs immediate medical attention. It is also important to know that some patients with acute leukemia (especially Acute Lymphocytic Leukemia or ALL) have the Philadelphia chromosome, but do not have CML. Treatment is different, though some strategies overlap for CML and ALL with the Philadelphia chromosome.

Statistics for Chronic Myeloid Leukemia

Chronic myeloid leukemia affects more adults than children and the chance of getting CML increases after age 65.

According to the American Cancer Society, almost 6,000 new cases of CML were diagnosed in 2014.

Symptoms of Chronic Myeloid Leukemia (CML)

Signs and symptoms of CML may look like other signs and symptoms of diseases or conditions.

If you have any, some, or all, of these symptoms*, please speak with your physician:

  • Pale skin
  • Shortness of breath
  • Tiredness, lethargy
  • Night sweats
  • Unexplained weight loss / loss of appetite
  • Enlarged spleen or liver (upon physician examination)

*From the Leukemia and Lymphoma Society

Other Names for Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) may also be referred to as chronic myelogenous leukemia, chronic myelocytic leukemia or chronic granulocytic leukemia.