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What Are the Risk Factors for Chronic Myelomonocytic Leukemia?

A risk factor is anything that changes your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for lung cancer and many other cancers. But people without any risk factors can still get the disease. And having a risk factor, or even several, does not mean that you will get the disease. Because chronic myelomonocytic leukemia (CMML) is rare, it has been hard to study. For a long time it was grouped with myelodysplastic syndromes. As a result, only a few risk factors are known for this disease.


The risk of CMML increases with age. This disease is rare in those younger than 40, with most cases found in people 60 and older.


In general, leukemia is more common in men than women. This includes CMML that is about twice as common in men as in women. The reason for this is not clear.

Cancer treatment

Prior treatment with chemotherapy seems to increase the risk of CMML. The risk of CMML after cancer chemotherapy, however, is not as high as the risk of other blood problems, such as myelodysplastic syndromes and acute myeloid leukemia. Second Cancers in Adults has more information on this.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Revised: February 27, 2024

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