Chronic myelogenous leukemia (CML)
Chronic myelogenous leukemia is a malignant cancer of the bone marrow. It causes rapid growth of the blood-forming cells (known as myeloid precursors) in the bone marrow, peripheral blood, and body tissues.
Causes, incidence, and risk factors
The disease can occur in adults (usually middle-aged) and children. CML affects 1 to 2 people per 100,000 and accounts for 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, like thyroid cancer or Hodgkin’s lymphoma. However, the vast majority of people treated for cancer with radiation DO NOT go on to develop leukemia. It takes many years to develop leukemia from this cause.
Chronic myelogenous leukemia is characterized by a chronic phase that can last for months or years. The disease may have few or no symptoms during the chronic phase. Eventually, the chronic phase progresses to a more dangerous “accelerated phase,” during which the leukemia cells grow more quickly.
Acceleration of the disease may be associated with fever (without infection), bone pain, and an enlarged spleen. Within 5 years, in most people, the disease then progresses to a “blast crisis,” when there is a very high count of immature white blood cells (leukemia cells). The blast phase of the leukemia is very difficult to treat. Bleeding and infection may occur due to bone marrow failure.
Other possible symptoms include:
- Excessive sweating (night sweats)
- Low-grade fever
- Pressure under the left ribs from an enlarged spleen
- Bleeding and bruising
- Sudden appearance of small red marks on the skin (petechiae)
Signs and tests
A physical examination often reveals an enlarged spleen.
- A CBC shows increased white blood cell count.
- A CBC differential is consistent with increased numbers of white blood cells, either mature or immature (depending on whether the disease is in the chronic or blast phase).
Additional signs and tests include:
- Bone marrow aspiration
- The presence of the Philadelphia chromosome
- The leukocyte alkaline phosphatase level
This disease may also alter the results of the following tests:
- Vitamin B-12 level
- Uric acid
- Platelet count
Treatment is aimed at reducing the growth of the leukemic cells in the bone marrow and may bring about a remission (when no leukemia can be found) with good control of the symptoms of the disease.
The chronic phase can be controlled with chemotherapy, which can be given as an outpatient. Interferon has been used to achieve temporary remission.
In 2001, the FDA approved a new drug for CML called imatinib (Gleevec), which is particularly effective when the disease has not responded to standard treatment (bone marrow transplant). This drug works directly on the leukemic cells to slow their growth. A bone marrow transplant preceded by high-dose chemotherapy and radiation therapy remains the standard treatment, however, although not all people with CML are suitable candidates for transplantation or have a suitable donor.
It is not known at the present time which patients should receive a bone marrow transplant as the first treatment and who should receive Gleevec. Participation in a medical study (“clinical trial”) comparing these treatments may be appropriate. Since treatment recommendations for CML are changing quickly with new research findings, you should discuss in detail with your oncologist the advantages and disadvantages of each option.
SELF CARE MEASURES
To minimize bleeding, apply ice and pressure to any external bleeding. A soft toothbrush and electric razor should be used for personal hygiene. An increase in calories and protein in your diet may help reduce the side effects associated with chemotherapy. Planning daily activities with scheduled rest periods can help to prevent the fatigue associated with anemia.
For additional information and resources, see cancer support group and leukemia support group.
Without curative treatment, the disease is always fatal. On average, the survival is 3 to 4 years. Over half of those who receive a bone marrow transplant have long-term, disease-free survival. The long-term survival after imatinib alone is not known.
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.
Calling your health care provider
Call your health care provider if you have symptoms suggestive 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.
by Harutyun Medina, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.