Clinical-cytogenetic correlations in myelodysplasia (preleukemia).

Cytogenetic studies detected abnormalities in 107 (43%) of the 247 patients in this series. Some degree of overt clinical progression occurred in 55 patients (22%), this being 29% of those patients with cytogenetic abnormalities and 17% of those with normal chromosomes. The presence and complexity of a clonal cytogenetic abnormality correlated with shorter survival. In each clone category of a complexity classification (simple, complex, very complex), patients with some normal cells appeared to have better survival than those with none. In multiple regression analyses, the prognostic value of chromosomes was independent of (and second in importance to) the FAB type of myelodysplastic syndrome (MDS) whichever chromosome classification was used. Patients with refractory anemia (RA) had the lowest incidence of chromosome abnormalities and no cases were found to have only abnormal cells (AA). A greater proportion of patients with refractory anemia with an excess of blasts (RAEB) and RAEB in transformation (RAEB-t) had clonal abnormalities. Morphology alone is not at present able to distinguish between RA or refractory anemia with ringed sideroblasts and similar disorders that may not be MDS in the strict sense. Demonstration of a clonal cytogenetic abnormality remains a positive indication of the presence of the neoplastic nature of the disease.