Blastic Transformation in Mexican Population With Chronic Myelomonocytic Leukemia

Chronic myelomonocytic leukemia (CMML) is the most aggressive of chronic leukemias, with short overall survival and a high transformation rate to acute leukemia. We investigated the factors related to blastic transformation in a Mexican population treated at a tertiary referral center.

The records of patients with a diagnosis of CMML from 2000 to 2015 were reviewed. A total of 54 patients were included, with a median age of 71 years and an overall survival of 16 months. The patients with incomplete data were excluded. IBM SPSS Statistics, version 21.0, software was used to perform the statistical analysis.

The rate of blastic transformation was 33% (18 patients), and the interval time to progression was 9 months (range, 0-87 months). Comparing the patients who did not undergo blastic transformation to those who did, those with progression to acute leukemia tended to be younger (age, 58 vs. 71 years; P = .001), to have a greater peripheral blood blast count (≥ 2% vs. 0%; P = .003), and were more likely to have immature myeloid precursors circulating in the peripheral blood (94% vs. 64%; P = .02). On multivariate analysis, younger age continued to be a statistically significant factor for progression (hazard ratio, 0.97; 95% confidence interval, 0.929-0.987).

Mexican patients with CMML that progressed to overt acute leukemia were considerably younger, with a higher tumor burden and short overall survival. In this population, it is important to consider more aggressive treatment at diagnosis, focusing on high-dose chemotherapy and hematopoietic stem cell transplantation within a short period.