Chronic myelogenous leukemia (CML)
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.
CML; Chronic granulocytic leukemia; Leukemia - chronic granulocytic (CML)
Causes, incidence, and risk factors
CML most often occurs in middle-aged adults and in 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.
Radiation increases the risk of developing CML. Exposure may occur from:
- High-dose radiation treatments used in the past to treat thyroid cancer or Hodgkin’s lymphoma
- Nuclear disaster
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 immature blood-forming cells (myeloid precursors) in the bone marrow, blood, and body tissues.
Chronic myelogenous leukemia is grouped into several phases:
- 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 tests done for other reasons.
If untreated, CML progresses to the blast crisis phase. Bleeding and infection may occur due to bone marrow failure. Other possible symptoms include:
Signs and tests
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
- Blood and bone marrow testing for the presence of the Philadelphia chromosome
This disease may also alter the results of the following tests:
- Platelet count
- Uric acid
Imatinib (Gleevec) is the first-line therapy for everyone with CML. Gleevec is a pill, taken by mouth. It is associated with very high rates of remission and survival. New medications similiar to Gleevec include dasatinib (Sprycel) and nilotinib (Tasigna).
Sometimes a chemotherapy medicine called hydroxyurea (Hydrea) is used temporarily to reduce the white blood cell count if it is very high at diagnosis.
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) or acute lymphoid leukemia (ALL).
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.
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.
Stem cell tansplantation should be considered in 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, including infection, bleeding, fatigue, unexplained fever, and kidney problems. Chemotherapy can have serious side effects, depending on the drugs used.
Calling your health care provider
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.
Abeloff MD, Armitage JO, Niederhuber JE, Kastan MB, McKenna WG, eds. Abeloff’s Clinical Oncology. 4th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 107.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.