Chronic myelomonocytic leukemia: natural history and prognostic determinants.

A retrospective clinical review of 41 patients with chronic myelomonocytic leukemia revealed a median age of 66 years and a male:female ratio of 2.4:1. The disease was preceded by a myelodysplastic syndrome of a different subtype in 24% of the patients and transformed into acute leukemia in 24%. Splenomegaly was present in 54% of the patients and reached massive proportions in 24%. Chromosomal abnormalities occurred in 34% of those studied, most commonly in the younger age group; the most frequent were trisomy 8, monosomy 7, and deletions involving the long arms of chromosomes 20 and X. Polyclonal hypergammaglobulinemia was detected in 47% of the patients in whom serum protein electrophoresis was done. The median survival was 3 years. With use of univariate analysis, the statistically significant prognostic determinants were hemoglobin level, the "modified Bournemouth score," and bone marrow blast cell percentage. When these factors were subjected to a multivariate analysis, only bone marrow blast cell percentage was an independent prognostic determinant. Orally administered hydroxyurea controlled leukocytosis and splenomegaly in some patients without affecting the overall prognosis.