What is cancer?

Although some cases of myelodysplastic syndrome (MDS) are linked to known risk factors, for most, the cause is unknown.

Risk factors for MDS

A risk factor is anything that affects a person's chance of getting a disease such as cancer. Different cancers have different risk factors. For instance, smoking is a risk factor for lung cancer and for many other cancers, too. But risk factors don't tell us everything. 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. Here are some of the risk factors that have been linked to MDS:

Earlier cancer treatment

Having had treatment with chemotherapy ("chemo") is the most important risk factor for MDS. Patients who have been treated with certain chemo drugs for cancer are more likely to get MDS. Getting these drugs along with radiation treatment increases the risk even more. MDS is also seen in patients who have had stem cell transplants (bone marrow transplants) because these patients get very high doses of chemo.

Genetic syndromes

Some bone marrow problems are caused by abnormal (changed) genes that have been passed on from one or both parents. People with these problems (called syndromes) are more likely to develop MDS.

Family history

In some families, MDS has been found to happen more often than would be expected.

Smoking

Smoking increases the risk for MDS. Many people know that smoking causes cancers of the lungs, mouth, and throat, but few also know that it can affect cells that do not come into direct contact with smoke. Substances in tobacco smoke that cause cancer get into the bloodstream and can affect many parts of the body.

Radiation and certain chemicals

Radiation and certain chemicals have been linked to MDS. Being exposed to a lot of radiation (such as from 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 oil and rubber industries can also increase the risk of getting MDS.

Age and sex

Age is a risk factor for MDS. This disease is rare in people younger than 40. Most cases are found in those older than 60. MDS is also more common in men than in women.