Chronic myelogenous leukemia is cancer that starts inside bone marrow, the soft tissue inside bones that helps form blood cells. The cancer grows from cells that produce white blood cells.

See also:

• Acute myeloid leukemia (CML)
• Chronic lymphocytic leukemia (CLL)
• Leukemia

CML can occur in adults (usually middle-aged) and children. The disease affects 1 to 2 people per 100,000 and makes up about 7 - 20% cases of leukemia. It is usually associated with a chromosome abnormality called the Philadelphia chromosome.

Exposure to ionizing radiation is one possible trigger for this chromosome abnormality. Such exposure could occur from a nuclear disaster or from treatment of a previous cancer such as thyroid cancer or Hodgkin's lymphoma. It takes many years to develop leukemia from this cause. However, most people treated for cancer with radiation do not go on to develop leukemia, and most patients with CML have not been exposed to radiation.

CML causes rapid growth of the blood-forming cells (myeloid precursors) in the bone marrow, blood, and body tissues.

Chronic myelogenous leukemia is grouped into several phases:

• Chronic
• Accelerated
• Blast crisis

The chronic phase that can last for months or years. The disease may have few or no symptoms during this time. Most people are diagnosed during this stage, when they are being tested for something else.

The accelerated phase is a more dangerous phase, during which the leukemia cells grow more quickly. This phase may be associated with fever (without infection), bone pain, and a swollen spleen.

If untreated, CML progresses to the blast crisis phase. Bleeding and infection may occur due to bone marrow failure. Other possible symptoms include:

• Fatigue
• Weakness
• Excessive sweating (night sweats)
• Low-grade fever
• Pressure under the left ribs from an swollen spleen
• Bleeding and bruising
• Sudden appearance of small red marks on the skin (petechiae)

A physical examination often reveals a swollen spleen. A complete blood count (CBC) shows an increased number of white blood cells.

Other tests that may be done include:

• CBC differential
• Bone marrow aspiration
• Genetic testing (for the bcr-abl gene)
• Testing for the presence of the Philadelphia chromosome

This disease may also alter the results of the following tests:

• Platelet count
• Uric acid
• Vitamin B12 level

Imatinib (Gleevec) is the first line of therapy for all patients. Gleevec blocks the Philadelphia chromosome and is assosicated with very high rates of remission. New medications include dasatinib (Sprycel) and nilotinib (Tasigna).

Sometimes a chemotherapy medicine called hydroxyurea (Hydrea) is used temporarily to control the white blood cell count. Note: Blast crisis phase is very difficult to treat, because it is marked by a very high count of immature white blood cells (leukemia cells).

The only known cure for CMS is a bone marrow transplant or stem cell transplantation. You should discuss your options in detail with your oncologist.

See:

• Cancer support group
• Leukemia support group

Since the introduction of Gleevec, the outlook for patients with CML has improved dramatically. When the signs and symptoms of CMS go away, you are said to be in remission. Many patients can remain in remission for many years while on this drug.

Transplantation should be considered in all patients. Long-term cure after transplantation ranges from 60 - 80%.

Blast crisis can lead to complications of CML, including infection, bleeding, fatigue, unexplained fever, and kidney problems. Chemotherapy can have serious side effects, depending on the drugs used.

Call your health care provider if you have symptoms of CML or have been diagnosed with CML and develop a fever higher than 100°F, chills, sore throat, or cough.

Avoid exposure to radiation when possible.

Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: pp. 1397-1407.