Background: The FAB group proposed to distinguish 2 subgroups of chronic myelomonocytic leukemia (CMML): Depending on the total leukocyte count a myelodysplastic type (< 13,000/microliter) was separated from a myeloproliferative type (> 13,000/microliter). Prognostic factors are not well-established until now.
Patients and methods: Based on retrospective analyses of patients with CMML diagnosed at our institution, we compared the presenting clinical and hematological features of both disorders and examined the natural course of the disease and prognostic factors.
Results: Out of 225 patients with CMML there were 115 patients with myelodysplastic type (MDS-CMML) and 110 patients with myeloproliferative type (MPD-CMML). Median age of patients at diagnosis and sex ratio were not different. Splenomegaly and hepatomegaly were more common in MPD-CMML. With regard to laboratory findings, patients with MPD-CMML presented with significantly higher LDH values. Except for WBC, peripheral blood counts were not different. Median percentage of bone marrow blasts was 8% in both disorders. Signs of bone marrow dysplasia were comparable in both disorders. Cumulative survival rates were similar in both disorders. Five years after diagnosis, actuarial survival for patients with MPD-CMML was 24%, as compared to 15% for patients with MDS-CMML. The probability of transformation to AML was higher in MDS-CMML (29% vs 18% after 5 years). Elevated LDH values, low hemoglobin values and male sex were independent risk factors for the entire group and for the MDS-CMML group. Using the Düsseldorf score, we could define risk groups within MDS-CMML with a median survial of 12 vs 40 months (p = 0.00005). Prognostic factors could not define risk groups within the MPD-CMML group.
Conclusions: In summary, these data suggest that MDS-CMML and MPD-CMML are clinically distinguishing conditions, but the separation provides little prognostic information. The Düsseldorf score can be used to provide risk stratification in CMML.