Mode of disease progression in primary myelodysplastic syndromes: A Japanese co-operative study

Abstract Chronological changes in hematological findings were analyzed in 225 patients with myelodysplastic syndromes (MDS). They were diagnosed between 1990 and 1992. Their hematological findings, i.e. hemoglobin levels, leukocyte and platelet counts, proportions of peripheral blood (PB) blasts and monocytes, and proportion of blasts in bone marrow (BM), were recorded for up to 42 months after diagnosis, when available. BM was examined regularly in only a few patients. Therefore, it was impractical to use the French-American-British Cooperative Group criteria for subtype classification during the disease course. Thus, we used the percentage of PB blasts as the only indicator of stage evolution. We classified the disease into four stages: stage 1, less than 1% PB blasts; stage 2, 1–5% PB blasts; stage 3, 5–30% PB blasts; and stage 4, 30% or more PB blasts. There were 171 patients initially in stage 1, 37 initially in stage 2, and 17 initially in stage 3. Less than half (45%) of the patients initially in stage 1 progressed to stage 2, while 91% of the patients initially in stage 2 and all of the patients initially in stage 3 showed stage evolution. Eight variables, i.e. BM blasts 5% or more, male sex, karyotypic abnormalities, micromegakaryocytes, mononuclear large megakaryocytes, platelet counts 50 × 10 9 /l or higher, abnormal nucleus of granulocytes, and abnormal granules of granulocytes, were found to be significant risk factors for evolution from stage 1 to 2. Evolution from stage 1 to a higher stage within 15 months of diagnosis was associated with impending poor prognosis in most patients. However, of the 67 patients initially in stage 1 who died, 30 did not show stage evolution. Evolution from stage 2 to a higher stage and from stage 3 to stage 4 was also associated with impending poor prognosis. Higher levels of cytopenia were not associated with poorer prognosis in the stage 1 patients. In conclusion, our grading system proved to be useful in evaluating the chronological changes in MDS patients.