Clinical characteristics of Japanese patients with primary myelodysplastic syndromes: a co-operative study based on 838 cases. Anemia Study Group of the Ministry of Health and Welfare.

The characteristics of Japanese (JPN) patients with myelodysplastic syndromes (MDS) were investigated in 838 retrospectively collected cases. The median age of the JPN patients was 60 years, about 10 years younger than that in most of the reports based on Western patients. Median survivals were 65 months for refractory anemia (RA), 58 months for RA with ring sideroblasts (RARS), 16 months for RA with an excess of blasts (RAEB), 10 months for RAEB in transformation (RAEBT), and 20 months for chronic myelomonocytic leukemia (CMML). Cumulative leukemia-free rates at final observation were 73% for RA, 79% for RARS, 24% for RAEB, 20% for RAEBT, and 53% for CMML. When low-risk (RA and RARS) patients were divided into two groups, those 40 years of age and older, and those under 40, the cumulative leukemia-free rate was 94% for the younger patients (n = 101), compared with 66% for the older patients (n = 318). The prognostic factors for survival were different from those in Western reports, i.e., variables representing quantitative abnormalities (hemoglobin levels, granulocyte, and platelet counts) were not major prognostic factors, while variables representing qualitative abnormalities (morphological abnormalities in granulocytic and megakaryocytic series cells) were highly significant. Two scoring systems for overall survival and for leukemic transformation were developed, based on multivariate prognostic factor analysis. Neither system included variables representing the degree of cytopenia. Whatever the reason for the different prognostic factors in JPN and Western MDS patients, the use of a scoring system based on Western patients for clinical decision-making in a JPN patient could be misleading, and vice versa.