Ethnic differences in prostate cancer survival in New Zealand: a national study

Objective: To examine disease-specific survival from prostate cancer by ethnic group in New Zealand. Methods: Analyses were based on the 7,733 men with histologically confirmed prostate cancer diagnosed from the start of 1996 to the end of 1999 in New Zealand. Five-year adjusted prostate-specific mortality rates and hazard ratios were calculated for Maori, Pacific, and European men. Results: In univariate analyses, Maori and Pacific men had higher mortality particularly in the first year after a diagnosis of prostate cancer than did European men. The strongest prognostic factors for prostate cancer were Gleason score and age. When survival analyses by ethnic group were adjusted for age and Gleason score the disparities in survival for Maori men and Pacific men with low-grade prostate cancers remained, with European men having the best survival. Conclusions: Several possible explanations have been proposed to explain the survival disparities by ethnicity in New Zealand. Differentials in Gleason grade of disease by ethnic group explain a lot of these disparities. Further data on stage of disease at diagnosis, co-morbidity, treatment, access to health services, and behavioral and environmental factors are needed to resolve these issues.