Asian race and impact on outcomes after radical radiotherapy for localized prostate cancer

Purpose: We compared survival outcomes in patients of Asian descent treated with curative intent radiation therapy for prostate cancer with that in the nonAsian population in British Columbia, Canada. Materials and Methods: Since 1994, 1,872 men treated with curative intent radiotherapy for prostate cancer have been followed prospectively at our-provincial institution, where cancer care delivery is coordinated for the province of British Columbia. Patients are treated uniformly based on provincial policies and guidelines. Patients were divided into 63 Asian (3.6%) and 1,804 nonAsian (96.4%) patients by surname with Asian names checked by telephone contact. Three risk groups were defined based on pretreatment prostate specific antigen, biopsy Gleason score and clinical T staging. For the whole cohort and each risk group survival was estimated using the Kaplan-Meier method and comparisons were made between the Asian and nonAsian populations. Results: The mean age of Asian and nonAsian men was 71.5 and 71 years, respectively. Median prostate specific antigen was 11.4 and 10 ng/ml, respectively (p = 0.7). Median Gleason score was 7 for Asian patients and 6 for nonAsian patients. (p = 0.002). There were twice the percentage of Asian patients with Gleason scores 8 or greater than nonAsians (26.5% vs 13.8%, p = 0.003). More Asian patients had stage 3 or 4 disease than nonAsians (44.8% vs 34.9%, p = 0.095). A greater proportion of Asian patients were classified as being at high risk than the nonAsian population (60.3% vs 47.6%, p = 0.04). For the entire cohort, and the low, intermediate and high risk groups there were no differences in time to first failure, or cause specific or overall survival for Asian vs nonAsian men. Conclusions: A greater proportion of patients of Asian descent present with high risk prostate cancer than nonAsian patients, which could be due to intrinsic biological differences and/or differences in diagnostic patterns. Survival outcomes after radiotherapy are the same for the 2 populations.