Background: Few well-established prostate cancer risk factors exist, and associations with modifiable factors, such as diet/nutrient intake and other health-related parameters, have primarily been identified in non-Hispanic white populations. In this study we examined whether prior associations explain prostate cancer risk in non-Hispanic black men and/or underlie some of the black-white difference in risk.
Methods: Race-specific associations between diet, nutrient intake, and other factors and prostate cancer risk in black (N = 7,030) and white (N = 230,968) men in the NIH-AARP cohort were examined. During an average of 9.4 years of follow-up, there were 1,049 incident cases among black men (156 advanced stage), and 21,301 cases among white men (2,677 advanced). Cox proportional hazards regression models estimated prostate cancer hazard ratios (HR) and 95% confidence intervals (CI). We also evaluated the change in the HR for black race following addition of each factor to the model.
Results: Race-specific parsimonious prostate cancer models showed similar black and white associations only for history of diabetes (black men HR = 0.79, 95%CI: 0.65-0.95; and white men HR = 0.72, 95% CI: 0.68-0.77). For all other risk factors examined, the associations were either similar but did not reach statistical significance in black men (i.e., for body mass index, smoking status, and tomato intake), or differed by race. For example, in white men we observed a null association with non-advanced disease for height (per 10 cm increase, HR = 1.01, 95% CI: 0.99-1.03), and an inverse association in black men (HR = 0.91, 95% CI: 0.82-0.996; p for interaction = 0.03). Similarly, a positive association was evident between dietary vitamin D intake and non-advanced disease in white men (highest versus lowest quintile, HR = 1.11, 95% CI: 1.05-1.18), with an inverse association in black men (HR = 0.88, 95% CI: 0.71-1.10; p for interaction = 0.04). Risk of advanced disease showed a null association with alcohol consumption in white men (≥ 6 drinks/day versus never drinkers, HR = 0.96, 95% CI: 0.78-1.20) and a statistically significant direct relation in black men (HR = 2.19, 95% CI: 1.04-4.59; p for interaction = 0.15). Overall, adjustment for the risk factors increased the hazard ratio for black race by 23% (1.73 to 1.90) for non-advanced and 13% (2.03 to 2.16) for advanced disease.
Conclusions: Our data suggest that many factors thought to influence prostate cancer risk in predominantly non-Hispanic white populations explain only a small proportion of black male risk, or the black-white difference in risk. Dietary vitamin D intake, height, and alcohol consumption associations with prostate cancer risk may vary between black and white men.
Citation Format: Tracy M. Layne, Barry I. Graubard, Xiaomei Ma, Susan T. Mayne, Demetrius Albanes. Prostate cancer risk factor profiles in black and white men in the NIH-AARP Diet and Health Study. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1777.