Chromosome studies in preleukemic states. V. Prognostic significance of single versus multiple abnormalities.

The prognostic value of marrow chromosome findings was examined in 242 patients with preleukemic myelodysplastic syndromes (MDS) or myeloproliferative disorders (MPD), with emphasis on the significance of single versus multiple karyotypic changes. In both groups, the results showed that patients with multiple chromosome abnormalities in a marrow clone had a very high probability of early death, from progression to leukemia or from other complications of hematopoietic dysfunction. Conversely, in patients with a hemic clone having only one karyotypic alteration (involving a single chromosome or single translocation), survival over 2 years was only slightly reduced as compared to those without chromosome abnormality. The only single karyotypic alteration perhaps associated with a markedly shortened survival was monosomy 7. These findings suggest that the conclusions of previous studies concerning the grave consequences of chromosome alterations in preleukemia largely reflect the clinical significance of clones with multiple cytogenetic changes. Prior knowledge of the karyotypic status of preleukemic patients should be helpful in evaluating current attempts to find effective treatment for these difficult disorders.