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 cancer of the lung and many other cancers. 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.

Cancer treatment

Prior treatment with chemotherapy is the most important risk factor for MDS. Patients who have been treated with certain chemotherapy drugs for cancer are more likely to develop MDS. 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
• etoposide, teniposide
• cyclophosphamide (to a lesser degree)
• doxorubicin. ( to a lesser degree)

Combining these drugs with radiation therapy increases the risk further. Secondary MDS seems to be more common after treatment for Hodgkin disease, non-Hodgkin lymphoma, or childhood acute lymphocytic leukemia. It develops less often after treatment of breast, lung, ovarian, testicular, gastrointestinal system, or other cancers. MDS is also seen in patients who have had stem cell transplants (bone marrow transplants) because these patients receive very high doses of chemotherapy

Genetic syndromes:

Some bone marrow problems are caused by abnormal (mutated) genes that have been passed on from one or both parents. People with these inherited syndromes are more likely to develop MDS. These disorders include Fanconi anemia, Shwachman-Diamond syndrome, familial platelet disorder, and severe congenital neutropenia.

Familial MDS

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

Smoking

Smoking increases the risk of MDS. Although many people know that smoking can cause cancers of the lungs, mouth, throat, and larynx, few realize that it can also affect areas that do not 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

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 also increase the risk of developing MDS.

Age

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

Sex

MDS is more common in men.