Regional variations in age at diagnosis and overall survival among patients with chronic myeloid leukemia from low and middle income countries.

INTRODUCTION: The epidemiology of chronic myeloid leukemia (CML) in low and middle income countries is limited. As a result, we analyzed a contemporary cohort of patients from low and middle income countries treated with Imatinib through The Glivec(®) International Patient Assistance Program (GIPAP).
METHODS: Generalized estimating equations (GEE) and Kaplan-Meier estimation were utilized to test for regional variations in age at diagnosis and overall survival among 33,985 patients from 94 countries.
RESULTS: Patients participated from Asia (79.2%), Africa (9.4%), Latin America (8.7%) and Southern/Eastern Europe (2.5%). Sixty-one (61.2%) percent were male. Mean age at diagnosis was 38.5 years (9.4% <20 years and only 4.7% ≥65 years). Using GEE, Asians were youngest (38.3 years), followed by Africans (39.5 years), Southern/Eastern Europeans (41.1 years) and Latin Americans (41.3 years; p < 0.0001). Diagnoses were predominately in chronic stage (78.3%). In 2002, 85.2% of patients had a delay in treatment >1 year; decreasing to 15.5% in 2010 (p < 0.0001). The 3-year overall survival probability was 89.4% (95% CI, 88.9-89.9). In multivariate analysis, risk of death increased among patients 65 years or older at diagnosis (p < 0.0001), time from diagnosis to treatment >1-year (p < 0.0001), diagnoses in the accelerated or blast crisis (p < 0.0001), initial dose of Imatinib >400 mg (p < 0.0001) and among Latin Americans and Africans (p < 0.0001).
CONCLUSION: The GIPAP cohort is the largest series of patients with CML described from low and middle income countries. Differences in age at diagnosis and overall survival exist within and between regions. Additional epidemiological studies should be conducted to assess for possible environmental factors associated with the earlier age at onset.