Patients With Therapy-Related CMML Have Shorter Median Overall Survival Than Those With De Novo CMML: Mayo Clinic Long-Term Follow-Up Experience

Background Chronic myelomonocytic leukemia (CMML) is a malignant hematologic neoplasm characterized by peripheral blood monocytosis and bone marrow dysplasia. The World Health Organization classified therapy-related (t-) myeloid neoplasm (MN) as another category. It is known that t-MNs tend to have a worse prognosis than de novo (dn-) MN (dn-MN). Patients and Methods Previous exposure to chemotherapy (CT), radiotherapy (RT), or both were defined as t-CMML and lack of both as dn-CMML. Results Of 265 CMML patients, 30 (11%) had t-CMML. Seventeen (57%) patients had previous exposure to CT, 6 (20%) to RT, and 7 (23%) to CT and RT. Leukemic transformation (LT) was seen in 5 (17%). In comparison, only lower platelet count was found to be statistically significant compared with dn-CMML. Median overall survival (OS) was 20 months in the dn-CMML group versus 11 months in the t-CMML group (P =.02). Median OS was 9 months in the CT group versus 4.4 months in the RT group versus 13 months in the CT and RT group (P =.7). Conclusion t-CMML comprises a small portion of all CMML cases (11%). Median OS in the dn-CMML group was longer than in the t-CMML group but LT seemed to be similar in terms of incidence and time to occurrence. Additional studies are needed to confirm our results.