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 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 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 having blood drawn for other reasons.

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:

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

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:

• Bone marrow aspiration and biopsy
• CBC with white blood cell differential
• 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 therapy for everyone with CML. Gleevec blocks the Philadelphia chromosome and is associated with very high rates of remission. New medications include dasatinib (Sprycel) and nilotinib (Tasigna). They work in a similar way as imatinib.

Sometimes a chemotherapy medicine called hydroxyurea (Hydrea) is used temporarily to control the white blood cell count.

The blast crisis phase is very difficult to treat, because it is marked by a very high count of immature white blood cells (leukemia cells). It is treated similarly to acute myeloid leukemia (AML).

The only known cure for CML is a bone marrow transplant or stem cell transplant. 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 CML 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 whose disease comes back after initial treatment with imatinib (Gleevec). 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.

Kantarjian H, O'Brien S. The chronic leukemias. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 195.

National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology: Chronic myelogenous leukemia. National Comprehensive Cancer Network; 2009. Version 2.2009.