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A risk factor is anything that increases your chance of getting a disease such as cancer. Different cancers have different risk factors. Some cancer risk factors, like smoking, you can change. Others, like your age or family history, can’t be changed.

But having a risk factor, or even several, does not always mean that a person will get the disease, and many people with cancer have few or no known risk factors.

There are several known risk factors for myelodysplastic syndromes (MDS).

Older age

MDS can occur at any age, even in children. But it is uncommon in people younger than 50, and it’s most often diagnosed in people in their 70s or 80s.

Male sex

MDS is more common in men than in women. The reason for this is not clear, although it might have to do with men having been more likely to smoke or to have been exposed to certain chemicals in the workplace in the past.

Cancer treatment

People who have been treated with certain chemotherapy (chemo) drugs or with radiation therapy for cancer are more likely to develop MDS later. When MDS is caused by cancer treatment, it is called secondary MDS or treatment-related MDS.

People who have had stem cell transplants (bone marrow transplants) can also develop MDS because of the very high doses of chemo (and possibly radiation) they received.

Still, only a small percentage of people who get chemo and radiation will eventually develop MDS.

Smoking

Smoking increases the risk of MDS. Many people know that smoking can cause lung cancer, but it can also cause cancer in other parts of the body that don't come into direct contact with smoke. Cancer-causing substances in tobacco smoke are absorbed into the blood as it passes through the lungs. Once in the bloodstream, these substances spread to many parts of the body.

Environmental exposures

Some environmental exposures have been linked to MDS. For example:

• High-dose radiation exposure (such as surviving an atomic bomb blast or nuclear reactor accident) increases the risk of developing MDS.
• Long-term workplace exposure to benzene and certain other chemicals used in the petroleum, rubber, and agricultural industries can also increase the risk of developing MDS.

Genetic syndromes

People with certain inherited syndromes are more likely to develop MDS. These syndromes are caused by changes (mutations) in genes that are passed down from one or both parents. Examples include:

• Fanconi anemia
• Bloom syndrome
• Down syndrome (Trisomy 21)
• Ataxia-telangiectasia
• Shwachman-Diamond syndrome
• Diamond Blackfan anemia
• RUNX1 familial platelet disorder with associated myeloid malignancies
• Severe congenital neutropenia (also called Kostmann syndrome)
• Dyskeratosis congenita

Many of these rare conditions are linked with MDS that develops during childhood.

Familial MDS

In some families without these syndromes, MDS occurs more often than would be expected. Sometimes this is because of a known gene mutation that runs in the family, but in other cases the cause isn’t clear.