[Myelodysplastic syndromes. The epidemiological and etiological aspects].

From a total of 18,416 bone-marrow biopsy reports entered into the Düsseldorf Bone Marrow Registry between 1975 and 1990 those of patients diagnosed as having preleukaemia, myeloid dysplasia, panmyelopathy with hypercellular bone marrow, refractory anaemia, sideroblastic anaemia or smoldering leukaemia were reanalyzed together with patient-data. If the diagnosis of myelodysplastic syndrome (MDS) was confirmed, the original blood and bone-marrow smear was re-examined and classified, 584 cases in all (3.2%). During the same period acute myeloid leukaemia had been diagnosed in 506 patients (2.8%). The average annual incidence of MDS in the Düsseldorf area was 3.65 per 100,000 inhabitants. Over 80% of cases occurred from the age of 60 years, while 7% were younger than 50 years. The sex ratio was the same in all subgroups of MDS, except chronic myelomonocytic leukaemia (male:female ratio 1:1.57). 31 patients (5.3%) had received ionizing radiation and/or cytostatic or immunosuppressive treatment for various underlying diseases before MDS had been diagnosed (secondary MDS). Preceding occupational contact with organic solvents could not be excluded with certainty in 12 patients. These data suggest that MDS is a relatively frequent disease of hematopoiesis among the older age groups. The proportion of secondary (treatment-induced) forms is small and does not explain the recently observed increased incidence.