Analysis of the Mortality of Russian Patients With Chronic Myeloid Leukemia in the Multicenter EUTOS ELN Population-based Study (EUTOS-PBS)

Abstract

Introduction: Russia took part in the multicenter population-based study (Europe) and included 6.8% adult patients with newly diagnosed chronic myeloid leukemia (CML). The objective of this study was to analyze the mortality in the Russian cohort of patients with newly diagnosed CML in the EUTOS PBS observational study.

Patients and methods: The analyzed cohort consisted of 197 patients (>18 years) with Ph+/BCR-ABL1+ CML diagnosed in the period from October 1, 2009 through December 31, 2012 from 6 regions of Russia. The distribution of the phases of CML were: chronic phase (CP), 93.4% and accelerated phase (AP) + blast crisis (BC), 6% + 0.6%. The median age was 50 years (range, 18-82 years); the male/female ratio was equal.

Results: The overall survival (OS) at 5, 6, and 7 years was 80% (95% confidence interval [CI], 72%-86%), 78% (95% CI, 65%-80%), and 73% (95% CI, 65%-80%), respectively (P < .001). The 5-year OS in patients with AP and BC was 39%. In Russia, the study was prolonged, with a median follow-up of 77 months (range, 0.7-108 months): 141 (71.5%) patients were alive, 47 (24%) patients died, and the status of 9 (4.5%) patients is was unknown. Forty-seven (23.8%) patients died during the follow-up period. The largest number of deaths was observed in the first year after the CML diagnosis: 17 (36%) of 47 cases, 3 of 17 died refusing the CML treatment. At the seventh year of CML therapy, 1 patient died after allogenic hematopoietic stem cell transplantation. The causes of death were: (1) progression of CML to AP/BC in 20 (43%) patients; (2) death in remission in 5 (11%) patients with complete cytogenetic response (CCyR) and/or major molecular response; and (3) death without progression to AP/BC but with signs of leukemia in 22 (46%) patients. The 5-year cumulative incidence of death from all reasons was 20%; the cumulative incidence of CML-related and non-CML-related death at the fifth year was 18% and 11%, respectively.

Conclusion: In general, the results of treatment in the Russian population sample of non-selected patients with CML were comparable with the data of the total European cohort. The CML-related deaths prevailed in the first year of CML therapy. The appropriate monitoring and therapy interventions during the first year of CML treatment are apparently important for the long-term treatment results.

Keywords: CML; Mortality; Overall survival; Population-based study; TKI.