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A risk factor is anything that changes your chance of getting a disease such as cancer. Different cancers have different risk factors. Some 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 get cancer without having any known risk factors.

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

Older age

Older age is one of the most important risk factors for MDS. MDS is uncommon in people younger than 50, and most cases are found in people in their 70s or 80s.

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 be exposed to certain chemicals in the workplace in the past.

Cancer treatment

Prior treatment with chemotherapy (chemo) is another important risk factor for MDS. Patients who have been treated with certain chemo drugs for cancer are more likely to develop MDS later on. When MDS is caused by cancer treatment it is called secondary MDS or treatment-related MDS.

Some of the drugs that can lead to MDS include:

• Mechlorethamine (nitrogen mustard)
• Procarbazine
• Chlorambucil
• Cyclophosphamide
• Ifosfamide
• Etoposide
• Teniposide
• Doxorubicin

The risk of secondary MDS varies based on the type and doses of drugs. It might also be affected by the type of cancer the chemo is treating. Combining these drugs with radiation therapy increases the risk further. People who have had stem cell transplants (bone marrow transplants) can also develop MDS because of the very high doses of chemo they received. Still, only a small percentage of people who are treated with these medicines will eventually develop MDS.

Genetic syndromes

People with certain inherited syndromes are more likely to develop MDS. These syndromes are caused by abnormal (mutated) genes that have been passed on from one or both parents. Examples include:

• Fanconi anemia
• Shwachman-Diamond syndrome
• Diamond Blackfan anemia
• Familial platelet disorder with a propensity to myeloid malignancy
• Severe congenital neutropenia
• Dyskeratosis congenita

Familial MDS

In some families, MDS occurs more often than would be expected. Sometimes this is due to a known gene mutation that runs in the family, but in other cases the cause isn’t clear.

Smoking

Smoking increases the risk of MDS. Many people know that smoking can cause cancer of the lungs, 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:

• 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 chemicals used in the petroleum and rubber industries can also increase the risk of developing MDS.