The Epidemiology of Myelodysplastic Syndromes

This review provides an overview of the current literature on epidemiologic findings in patients with myelodysplastic syndromes (MDS). Based on the data of local registries and large-scale epidemiologic surveys, the annual incidence of MDS is approximately 4-5 cases per 100,000 people in developed countries. This figure might be underestimated because the diagnosis of MDS in elderly patients presenting with anemia of unknown etiology is often not confirmed because of the reluctance of patients and physicians to perform bone marrow examinations. Because the identification of nonblastic MDS types requires a particular diagnostic expertise, they are not unequivocally discernible from cases of secondary anemia and are therefore probably underrated. There is no evidence of an increasing age-adjusted incidence of MDS, but the absolute number of patients with MDS might increase in parallel with the demographic changes we currently witness. There is only a small number of patients with MDS who have a history of exposure to compounds known for their myelotoxic effects, such as benzene and radiation. Still, approximately 10% of patients with MDS develop the treatment-associated disease as a result of previous cytotoxic chemotherapy, radiation therapy, or a combination of both. The proportion of patients with treatment-associated MDS might increase in the future as a result of better and longer survival times of patients following more effective cancer treatment.