Prognosis of chronic myelomonocytic leukemia

Cytopenia caused by ineffective hematopoiesis and monocyte overproduction coexist in CMML, providing grounds for discussion to supporters of a dysplastic versus a proliferative identity for CMML. Follow-up information from a large series of patients may contribute to clarifying the position of this infrequent disease.

We analyzed data from 77 patients followed in five institutions. Thirty-two variables were studied for their influence on survival and on progression to acute leukemia by univariate and multivariate analysis. For some parameters, we performed a quartile analysis to reveal a possible non-monotonic influence on survival.

Median survival was 17 months. Evolution to acute leukemia (ANLL) occurred in 11 patients (14%) within a median time of 8 months. Multivariate analysis assigned a poorer prognosis to patients presenting with thrombocytopenia, anemia and leukocytosis. Thrombocytopenia and the presence of circulating blasts were risk factors for transformation to ANLL, while raised serum aspartate transaminase at diagnosis seemed to be associated with a lower probability of blastic evolution. The Bournemouth score for CMML proved to be a valid tool for predicting survival but not acute transformation.

CMML is a severe disease. The prognostic independence of cytopenia (anemia, thrombocytopenia) and leukocytosis underlines the coexistence of aspects typical of myelodysplastic and myeloproliferative syndromes.