About chronic myeloid leukemia (CML)

Chronic myeloid leukemia, or CML, is a cancer that occurs when the blood-forming cells of the bone marrow (the soft, spongy tissue in the center of bones) make too many white blood cells, including immature ones.

Approximately 95% of people living with CML have a genetic mutation that produces an abnormal chromosome in bone marrow stem cells, known as the Philadelphia chromosome (abbreviated “Ph chromosome” or simply “Ph”). The Ph chromosome carries a gene called BCR-ABL, which produces a protein of the same name.

The BCR-ABL protein triggers bone marrow to keep making abnormal versions of white blood cells, which are the leukemia cells. The resulting uncontrolled growth of these leukemia cells can cause a large increase in their concentration in the blood. Over time, these abnormal cells crowd out healthy red blood cells and platelets as well as normal white cells, which can have negative effects on your health.

Managing CML

Over the past two decades, the introduction of therapies that target the cancer-causing proteins and cells with the Ph+ chromosome to slow the reproduction of leukemia cells has helped transform outcomes in the course of a fatal blood cancer. Some patients who respond well to treatment may achieve a level of leukemic cells that is nearly undetectable; however, many patients remain at risk of disease progression. The sequential use of currently available therapies is associated with treatment resistance and/or intolerance.

If you have questions about the management of your CML, or are struggling with symptoms or treatment side effects, you should talk to your doctor.

As with any condition, it is important to take your medication as prescribed and directed by your doctor. It is also important to continue regular testing at each step of your journey, as this will enable you and your doctor to see if your treatment is working.

Additional resources

•    Understanding CML backgrounder (PDF 0.2 MB)


CML heritage story video