Introduction

Myelodysplastic syndromes (MDS) are a group of conditions caused by abnormal bone marrow cells. MDS was not been considered to be a kind of cancer in the past. But most cancer specialists now classify MDS as a cancer because it produces a large population of abnormal cells from a single, abnormal cell. These abnormal cells are exactly alike, and they all grow abnormally. This kind of growth is typically seen in cancer. About 10,000 to 15,000 new cases of MDS are diagnosed each year in the United States, usually in people older than 60.

In MDS, the stem (immature) cells in the bone marrow do not mature into healthy red blood cells, white blood cells, or platelets (small blood cells needed for clotting). The immature blood cells, called blasts, do not function normally and either die in the bone marrow or soon after they enter the blood. This leaves less room for healthy white blood cells, red blood cells, and platelets to develop in the bone marrow.

MDS can cause many different signs and symptoms, including weight loss, fever, and loss of appetite. Shortages of red blood cells (anemia) can cause tiredness, shortness of breath, and pale skin. Shortages of white blood cells can cause serious infections with high fevers. When patients do not have enough blood platelets to plug holes in damaged blood vessels, they may experience bruising and bleeding, including frequent or severe nosebleeds or bleeding in the gums.

The only suspected lifestyle-related risk factor for MDS is smoking. Patients who have been treated for other kinds of cancer with certain chemotherapy drugs are also more likely to develop MDS. Another risk factor for MDS is exposure to certain environmental factors, such as radiation and certain chemicals (including pesticides and solvents such as benzene).