Because CML often does not cause any symptoms in the early stage of the disease, "the most common way a person who is later diagnosed with CML comes to attention is by a routine complete blood count done for some unrelated reason, for example, through a routine physical or preoperative testing," says Dr. Kalaycio.
When symptoms do present, they tend to be general, flu-like symptoms such as:
- Night sweats
- Weight loss
- Bone pain
- Pain on the left side of the abdomen
- Feeling full quickly or inability to eat large amounts of food (caused by an enlarged spleen)
Most often a blood test or a bone marrow test is used to test for and diagnose CML. A bone marrow test requires that a small sample of bone marrow be removed for testing. This is done by either a bone marrow biopsy or bone marrow aspiration procedure. Often a bone marrow biopsy and bone marrow aspiration are performed at the same time.
Because it is currently unknown what causes CML, presently there are no known ways to prevent chronic myelogenous leukemia.
Chronic myelogenous leukemia has three distinct phases:
- Chronic phase CML: This is the first phase of the disease and indicates that fewer than 10 percent of the cells in the blood and bone marrow are blast cells (the diseased, immature white blood cells). More than 80 percent of people who are diagnosed with CML are diagnosed during the chronic phase. When treatment with medications is started in this phase, chance for remission is very high. Chronic phase typically lasts for five to six years before the disease progresses to accelerated phase.
- Accelerated phase CML: This is the second phase of the disease and indicates that 10 to 19 percent of the cells in the blood and bone marrow are blast cells. Symptoms have usually developed by this phase and may include anemia as well as general fatigue, malaise and other flu-like symptoms. The goal in treating accelerated CML is to kill all cells that contain the BCR-ABL gene or to return a person's blood count to that of the chronic phase.
- Blast phase CML (also called blastic phase or blast crisis phase CML): This is the third and final stage of the disease. In blast phase, 20 percent or more of the cells in the blood or bone marrow are blast cells. Symptoms such as fatigue, fever and an enlarged spleen typically occur during the blast phase. Similar to accelerated phase, the goal in treating blast phase CML is to kill all cells that contain the BCR-ABL gene or to return a person's blood count to that of the chronic phase.
Currently, chronic phase CML is almost always treated with imatinib (Gleevec). Gleevec, which was approved in 2001 as front-line treatment for CML, is a type of drug called a tyrosine kinase inhibitor and works by blocking the tyrosine kinase enzyme which produces the disease white blood cells (blast cells). The 8-year survival rate for Gleevec is 85 percent, meaning that the disease is in remission for 85 percent of people who have been taking Gleevec since the drug was first approved. About 15 to 20 percent of people with chronic phase CML are not able to take Gleevec either because they don't respond to treatment or they cannot tolerate the side effects, according to Dr. Kalaycio.
The goal in treatment of chronic phase CML is to kill all cells that have the BCR-ABL cancer gene and bring blood cell levels to a normal range.
In June 2010, the FDA approved the drug nilotinib (Tasigna) to treat newly diagnosed adult patients with chronic phase CML who test positive for the Philadelphia chromosome (Ph+ CP-CML). Recent clinical trials showed that Tasigna works better than Gleevec in as front-line treatment for chronic phase CML. Prior to this new indication, Tasigna has been approved since 2007 to treat adults with chronic phase CML who test positive for the Philadelphia chromosome and do not respond to Gleevec, or for adults with accelerated phase CML.
The drug dasatinib (Sprycel) is also approved by the FDA to treat people who don't respond to Gleevec. A recent study showed that Sprycel also works better than Gleevec as initial treatment for chronic phase CML. These results may lead the FDA to consider an expanded indication for Sprycel, similar to that of Tasigna.
Once a person has started medication treatment for CML, he or she must continue taking the drug(s) for the rest of their life or for as long as they are responding to the treatment.
If drug therapy (including switching drugs) doesn't bring chronic phase CML into remission with 18 months, stem cell transplantation is considered.
Accelerated or blast phase CML may be treated with Gleevec, Tasigna or Sprycel or other types of drugs such as interferon. If a person doesn't respond to medication or he is diagnosed with a T315I mutation (a mutation of the Philadelphia chromosome), stem cell transplantation is considered.
Side effects are different for each type of medication, but generally include nausea, swelling, diarrhea and other symptoms.