A risk factor is anything that increases 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 cancers of the lung, mouth, larynx, bladder, kidney, and several other organs. But having a risk factor, or even several, does not mean that you will get the disease.

Smoking: The only suspected lifestyle-related risk factor for myelodysplastic syndromes (MDS) is smoking. Although many people know that smoking is responsible for most cancers of the lungs, mouth, throat, and larynx, few realize that it can affect cells that do not come into direct contact with smoke. For example, smoking is a known risk factor for acute myeloid leukemia. Cancer-causing substances in tobacco smoke are absorbed into the blood that circulates through the lungs. Once in the bloodstream, these substances spread to many parts of the body.

Environmental exposures: Environmental risk factors, such as radiation and certain chemicals, 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 increase your risk of developing MDS.

Cancer treatment: This is the most important risk factor for MDS. Patients with other cancers treated with certain chemotherapy drugs are more likely to develop MDS. The drugs most often associated with secondary (post-treatment) MDS include mechlorethamine, procarbazine, chlorambucil, etoposide, teniposide, and, to a lesser degree, cyclophosphamide and doxorubicin. Combining these drugs with radiation therapy increases the risk further. Most of these cases of secondary MDS occur after treatment for Hodgkin disease, non-Hodgkin lymphoma, or childhood acute lymphocytic leukemia. They develop less often following treatment of breast, lung, ovarian, testicular, gastrointestinal system, or other cancers.

Now doctors are seeing cases of MDS in patients who have had stem cell transplants (bone marrow transplants) because these patients first receive very high doses of chemotherapy.

Congenital diseases: Fanconi anemia is a rare, inherited disorder associated with a greatly increased risk of developing leukemia or MDS as a child or young adult. These patients typically have shortages of one or more types of blood cells (white blood cells, red blood cells, and platelets) and may also have malfunctions of limbs and internal organs. Other findings include light or dark spots on the skin, shorter height than expected for the child's age, and deafness.

Familial MDS: MDS has been found to occur frequently in adults in some families.

Age: Perhaps the greatest risk factor is age. MDS is a disease of aging, and most patients are elderly – typically over 60.

Sex: MDS is slightly more common in men.

Revised: 12/07/2006