Chronic myelogenous leukemia (CML), also known as chronic myeloid leukemia and chronic granulocytic leukemia, is a slow-progressing cancer of the blood cells.
An uncommon cancer, CML affects the myelogenous cells of the body, starting with a change to a single stem cell. Patients develop an abnormal “Philadelphia Chromosome,” or Ph chromosome, named after the city in which it was discovered. This happens when one chromosome breaks and switches sections with another.
This chromosome then allows the production of too many white chromosomes, of which most contain the abnormal gene. These cells then overcrowd the normal cells, damaging the bone marrow. The Ph chromosome is not present in all CML patients, but does occur in 90% of cases. While CML can occur at any age, it normally occurs in older adults and rarely affects children.
Chronic Myelogenous Leukemia Risk Factors
While the causes of developing the Philadelphia Chromosome are not yet fully understood, scientists have discovered a number of risk factors that may aid in the development of chronic myelogenous leukemia:
- Age: The older a person is, the higher their risk. CML does not usually occur in children.
- Gender: Males have a higher risk of developing CML.
- Radiation Exposure: Being exposed to certain types of radiation, such as other cancer therapies or atomic radiation, can increase risk of development.
Many CML patients have none of the aforementioned risks. Family history is not believed to be a risk factor. The Ph chromosome is not believed to be present at birth, but developed later on in life. Medical and dental x-rays also do not cause the disease, and it is not contagious.
Chronic Myelogenous Leukemia Signs and Symptoms
In early stages, signs and symptoms of chronic myelogenous leukemia may not be present. Some patients live with the disease for months, or even years, without even suspecting it. However, once symptoms do occur they may include:
- Frequent Infections
- Loss of Appetite
- Enlarged Spleen
- Weight Loss
- Pain or Fullness Below Left Ribs
- Stomach or Bone Pain
- Easy Bleeding
- Night Sweats
- Stroke or Excess Blood Clotting
- Anemia (During Accelerated Phase)
- Death (If Untreated)
Chronic Myelogenous Leukemia Diagnosis
About 4,800 people are diagnosed with CML annually, and over 21,000 people currently live with the disease. Lab tests are used to both make a diagnosis as well as check the patient’s response to treatment. Tests may include:
- Physical Exam: While checking a patient’s blood pressure, pulse and other vital signs, a doctor will feel the spleen, lymph nodes and abdomen to check for abnormalities.
- Blood Tests: A CBC (complete blood count) may reveal blood cell abnormalities.
- Bone Marrow Aspiration and Biopsy: These will be used to gather bone marrow samples for laboratory tests. The aspiration is conducted through removing a small amount of bone marrow from the hipbone with a needle; the biopsy involves removing a part of the bone itself. These procedures can be done in a doctor’s office.
- Specialized Tests: Tests such as a fluorescence in situ hybridization (FISH) analysis and polymerase chain reaction (PCR) test may be used to check bone marrow samples for the Ph chromosome.
Chronic Myelogenous Leukemia Staging / Phasing
Once detected, doctors must find out what stage of development a patient’s CML is at to determine what treatment is needed. This will be done by comparing the number of healthy cells to the number of diseased cells.
A patient may be diagnosed with one of three different phases of CML:
Chronic: The earliest of the phases, the chronic phase has the best response to treatment.
Accelerated: During this accelerated phase, CML starts becoming more aggressive.
Blastic: This severe phase is the most aggressive, and marks where CML become life-threatening.
Chronic Myelogenous Leukemia Treatment
Like other forms of leukemia treatment, the goal of treating chronic myelogenous leukemia is to kill as many cancer cells as possible and return the blood cell levels to normal. If the patient is in the accelerated phase, the goal may be to return to the chronic phase.
Treatments may include:
- Administering Targeted Drugs: These drugs attack specific weaknesses of cancer cells, making them weaker and easier to kill. Drugs given to CML patients include Imatinib (Gleevec), Dasatinib (Sprycel), and Nilotinib (Tasigna). Most patients will continue to take the drug(s) given to them even during remission.
- Stem Cell Transplants: A blood stem cell transplant, typically used on patients for whom no other treatments have been successful, replaces diseased cells by forming new, healthy cells. This treatment is the only one that may result in a cure.
- Chemotherapy: Combined with other therapies, chemotherapy drugs are typically given by mouth for CML patients.
- Biological Therapy: By using a patient’s own immune system, biological drugs may help reduce leukemia cell growth.
Chronic Myelogenous Leukemia Outlook (Prognosis)
Of the patients who receive a transplant, 50% will remain in remission; 20% will relapse within five years after treatment. If left untreated, or if treatment fails, chronic myelogenous leukemia is fatal.
Chronic Myelogenous Leukemia Prevention
Since the causes of development are not fully understood, there are not may ways of preventing chronic myelogenous leukemia. By staying away from radiation and seeing a physician regularly, chances may be reduced, and any developments caught early may result in a more successful treatment.
Chronic Myelogenous Leukemia Resources
Mayo Foundation for Medical Education and Research (MFMER). 1998-2009. Retrieved May 1, 2009
The Leukemia & Lymphoma Society. April 30, 2009. Retrieved May 1, 2009
MedicineNet, Inc. April 29, 2000. Retrieved May 1, 2009