Chronic myeloid leukemia (CML), also known as chronic myelogenous leukemia, often comes with a good prognosis. Effective treatments can help many people with CML have positive outcomes and live for many years. To predict your outlook, your doctor will take into account prognostic factors that can affect how CML progresses. Additionally, the treatments that you receive play a role in your outcome.
The five-year survival rate for people with CML in the United States is 70.4 percent. This means that 70.4 percent — 70 out of 100 people — will live for at least five years after being diagnosed with CML. This number is estimated using large groups of people. It doesn’t tell you what exactly your outlook will be. Your health care team can help you better understand your outcome.
The five-year survival rate for CML has drastically improved in the past couple of decades. In the 1970s, only about 22 percent of people were alive five years after diagnosis. This means that the survival rate is now more than three times higher than it used to be. One of the main reasons for this is that researchers have developed new drugs that often lead to very good outcomes. The first of these drugs was Gleevec (imatinib), approved in 2001 for people with CML. Now, other similar drugs like Sprycel (dasatinib) and Tasigna (nilotinib) are also very effective at treating CML.
Previously, researchers estimated that people with CML lived for an average of four to six years after being diagnosed. However, new treatments have greatly improved the life expectancy of people living with CML. Researchers are still studying this topic, but they now predict people with CML may have a normal life span.
Certain risk factors can influence your outcome. Your doctor may use these factors to estimate your prognosis and determine whether aggressive treatments may be a good idea. Prognostic factors may be measured with different tests during the diagnosis of CML.
When predicting your outlook, your doctor will consider the phase of your CML. Your phase is determined by how many cells in your blood and bone marrow (tissue found inside your bones) are blast cells. Blasts are immature white blood cells. There are three CML phases:
People with accelerated or blast phase CML have a worse prognosis than people with chronic phase CML.
Men are more likely than women to develop CML. Additionally, men have an increased chance of having a worse outlook. Data from people with CML living in England show:
If you are in good health, you may be able to tolerate more aggressive treatments that can kill more leukemia cells. On the other hand, if you have other health problems, you may not be able to tolerate the side effects of stronger treatments. People who are in poorer health often need to use milder treatments.
Doctors evaluate overall health using a measure called performance status. Your performance status is an estimate of how well you can complete daily activities. If you have a hard time performing everyday tasks, you may have a worse CML prognosis.
Doctors use blood tests to determine your levels of different types of blood cells. High or low levels of certain cells can increase your chance of having a worse prognosis. One type of cell that your doctor will look closely at is cancerous blast cells. Having high levels of blasts in the blood is a sign of a worse outcome.
Levels of healthy blood cells also play a role in determining your prognosis. If you have anemia (low red blood cell counts) when you are diagnosed with CML, you have an increased chance of having a worse outcome. Levels of platelets (cell fragments that make blood clots) also play a role in prognosis. Very low or very high numbers of platelets may lead to a poor outlook. Finally, if you have high basophil or eosinophil counts, your doctor may estimate that you have a worse prognosis. Eosinophils and basophils are types of white blood cells that play a role in the body’s response to infections and allergies.
When diagnosing CML, your doctor may perform blood tests to measure your levels of lactate dehydrogenase (LDH). Various tissues in your body make LDH when they become damaged by a disease like cancer. High LDH levels can be a sign of a worse outcome for people with CML.
Splenomegaly (an enlarged spleen) is the most common sign of CML. More than half of people with CML have splenomegaly. Having an enlarged spleen increases your chances of having a poor outcome.
CML, like other cancers, develops when cells undergo certain gene changes. Your doctor can look for these gene changes using a variety of genetic tests. These tests may be performed when you are diagnosed with CML.
Nineteen out of 20 people with CML have a specific gene change called the Philadelphia chromosome. This gene change happens when part of one chromosome (long piece of DNA) breaks off and attaches to a different chromosome. The Philadelphia chromosome contains an abnormal gene called BCR-ABL.
People with CML who do not have the Philadelphia chromosome have a worse outlook. The most effective treatment for most cases of CML is a tyrosine kinase inhibitor (TKI) such as Gleevec (imatinib). TKIs block BCR-ABL, which kills leukemia cells. When CML cells don’t have BCR-ABL, TKIs may not be as effective.
Researchers have found that people with CML who do not have the Philadelphia chromosome have their own set of prognostic factors. Things that lead to a worse outcome in people without this gene change include:
Sometimes, the abnormal BCR-ABL gene can undergo additional changes. These changes cause TKI medications to not be as effective. One of the mutations that causes the most resistance to treatment is called T315I. People with this mutation often have much worse outcomes.
Some people with CML develop changes in other genes besides BCR-ABL or have other chromosome changes along with the Philadelphia chromosome.
One study found that certain chromosome abnormalities lead to worse outcomes for people with blast phase CML. These include:
Doctors recommend a few different therapies for the treatment of chronic myeloid leukemia. Some of these treatments lead to longer or shorter survival compared with the overall average survival rate.
Most people with CML have a positive prognosis when they take Gleevec (imatinib). For 80 percent to 90 percent of people with chronic phase CML, imatinib therapy eliminates leukemia cells. Imatinib also usually reduces other CML symptoms. The five-year survival rate for people taking imatinib is 90 percent.
Stem cell transplants can sometimes cure CML, eliminating all leukemia cells for good. A person’s outcome after a stem cell transplant depends on their CML phase:
Talk to your doctor to learn more about what to expect from different treatment options. Depending on your prognostic factors, certain treatments may be more effective for you.
Read more about CML treatment options here.
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