CLINICAL IMPLICATIONS OF CHROMOSOMAL-ABNORMALITIES IN 401 PATIENTS WITH MYELODYSPLASTIC SYNDROMES - A MULTICENTRIC STUDY IN JAPAN

It is well known that cytogenetic analysis in patients with myelodyspl astic syndrome (MDS) provides information useful in determining their prognosis. Based on the chromosomal results obtained from 401 MDS pati ents by a multicentric study in Japan, we studied correlations between chromosomal findings and prognosis or leukemic transformation in MDS patients. Patients with complex aberrations (cytogenetic abnormalities at more than three chromosomes), of any subtype, had a poor prognosis ; for example, >60 % of patients with refractory anemia (RA) showing c omplex aberrations died within one year, but only 11 % of them develop ed leukemia. In patients with RA with ringed sideroblasts (RARS), >70 % of those with complex aberrations evolved into the leukemic phase an d survived for less than one year, suggesting a biologic heterogeneity in RARS patients. By contrast, about 5 % of patients with RA or RARS exhibiting chromosomal findings other than -7/7q-, +8, two aberrations , and complex aberrations, developed leukemia and had a favorable prog nosis. Therefore, the presence of chromosome abnormalities alone in pa tients with RA or RARS is not a factor in predicting leukemic transfor mation or poor prognosis. In patients with refractory anemia with an e xcess of blasts (RAEB), the presence of chromosome aberrations at MDS diagnosis affected the occurrence of leukemic transformation (24 % ver sus 43 %), however, no particular difference was noted in patients wit h RAEB in transformation with regard to whether they had chromosome ch anges or not, and about 60 % of them evolved into leukemia. The poor p rognosis related to complex aberrations was consistently noted in all MDS subtypes or age-matched groups, indicating that this cytogenetic a nomaly is an independent risk factor for a poor prognosis in MDS patie nts. The duration between MDS diagnosis and development of the leukemi c phase and that between the latter and death were significantly short er in patients with complex aberrations than those without this change . Although the clinical significance of certain chromosomal abnormalit ies differs among subtypes of MDS, a new scoring system for predicting prognosis by cytogenetic changes, in combination with hematologic par ameters, was proposed.