Survival disparities between Ma¯ori and non-Ma¯ori men with prostate cancer in New Zealand

Abstract

Objective To examine temporal trends and current survival differences between Ma¯ori and non-Ma¯ori men with prostate cancer in New Zealand (NZ). Patients and Methods A cohort of 37 529 men aged ≥40 years diagnosed with prostate cancer between 1996 and 2010 was identified from the New Zealand Cancer Registry and followed until 25 May 2011. Cause of death was obtained from the Mortality Collection by data linkage. Survival for Ma¯ori compared with non-Ma¯ori men was estimated using the Kaplan-Meier method, and Cox proportional hazard regression models, adjusted for age, year of diagnosis, socioeconomic deprivation and rural/urban residence. Results The probability of surviving was significantly lower for Ma¯ori compared with non-Ma¯ori men at 1, 5 and 10 years after diagnosis. Ma¯ori men were more likely to die from any cause [adjusted hazard ratio (aHR) 1.84, 95% confidence interval (CI) 1.72-1.97] and from prostate cancer (aHR 1.94, 95% CI 1.76- 2.14). The aHR of prostate cancer death for Ma¯ori men diagnosed with regional extent was 2.62-fold (95% CI 1.60-4.31) compared with non-Ma¯ori men. The survival gap between Ma¯ori and non-Ma¯ori men has not changed throughout the study period. Conclusion Ma¯ori men had significantly poorer survival than non-Ma¯ori, particularly when diagnosed with regional prostate cancer. Despite improvements in survival for all men diagnosed after 2000, the survival gap between Ma¯ori and non-Ma¯ori men has not been reduced with time. Differences in prostate cancer detection and management, partly driven by higher socioeconomic deprivation in Ma¯ori men, were identified as the most likely contributors to ethnic survival disparities in NZ.