Understanding chronic myeloid leukemia
Learning that you have cancer can be overwhelming. But statistics show positive survival rates for those with chronic myeloid leukemia.
Chronic myeloid leukemia, or CML, is a type of cancer that begins in the bone marrow. It develops slowly in the blood-forming cells inside the marrow and eventually spreads through the blood. People often have CML for quite some time before noticing any symptoms or even realizing they have cancer.
CML seems to be caused by an abnormal gene that produces too much of an enzyme called tyrosine kinase. Although it’s genetic in origin, CML is not hereditary.
There are three phases of CML:
- Chronic phase: During the first phase, the cancer cells are growing slowly. Most people are diagnosed during the chronic phase, usually after blood tests done for other reasons.
- Accelerated phase: The leukemia cells grow and develop more quickly in the second phase.
- Blastic phase: In the third phase, the abnormal cells have grown out of control and are crowding out normal, healthy cells.
During the chronic phase, treatment usually consists of oral medications called tyrosine kinase inhibitors or TKIs. TKIs are used to block the action of the protein tyrosine kinase and stop the cancer cells from growing and multiplying. Most people who are treated with TKIs will go into remission.
If TKIs aren’t effective, or stop working, then the person may move into the accelerated or blastic phase. A stem cell transplant or bone marrow transplant is often the next step. These transplants are the only way to actually cure CML, but there can be serious complications. For this reason, transplants are typically only done if medications aren’t effective.
Like most diseases, the outlook for those with CML varies according to many factors. Some of these include:
- which phase they are in
- their age
- their overall health
- platelet counts
- whether the spleen is enlarged
- amount of bone damage from the leukemia
Cancer survival rates are typically measured in five-year intervals. According to the National Cancer Institute, overall data shows that almost 65.1 percent of those who are diagnosed with CML are still alive five years later.
But new drugs to combat CML are being developed and tested very quickly, increasing the likelihood that future survival rates may be higher.
Most people with CML remain in the chronic phase. In some cases, people who do not receive effective treatment or don’t respond well to treatment will move to the accelerated or blastic phase. Outlook during these phases depends on which treatments they have already tried and which treatments their bodies can tolerate.
The outlook is rather optimistic for those who are in the chronic phase and are receiving TKIs.
According to large 2006 study of a newer drug called imatinib (Gleevec), there was an 83 percent survival rate after five years for those who received this drug. A 2018 study of patients consistently taking the drug imatinib found that 90 percent lived at least 5 years. Another study, conducted in 2010, showed that a drug called nilotinib (Tasigna) was significantly more effective than Gleevec.
Both of these drugs have now become standard treatments during the chronic phase of CML. Overall survival rates are expected to increase as more people receive these and other new, highly effective drugs.
In the accelerated phase, survival rates vary widely according to treatment. If the person responds well to TKIs, rates are nearly as good as for those in the chronic phase.
Overall, survival rates for those in the blastic phase hover below 20 percent. The best chance for survival involves using drugs to get the person back into the chronic phase and then trying a stem cell transplant.