Examining the Role of Adiposity in Racial and Ethnic Disparities in Prostate Cancer

Background: Men of predominant African ancestry have the highest rates of prostate cancer (PCa), globally. In the United States, PCa incidence in Black men is 1.5 times the incidence in all other races combined, and 1.6 times that of their White counterparts. The death rate in Black men is 2.3 times the rate in all other races, and 2.4 times that of White men. Various biologic, behavioral, demographic, contextual, and environmental factors are suggested components of persisting PCa disparities. The contribution of body composition, including body mass index (BMI), to racial and ethnic disparities in PCa occurrence and course remains unclear. Objective: The overarching objective of this work was to use available data to clarify the role of adiposity in prostate cancer occurrence and course, with special consideration for its role in the incidence and outcomes disparities observed among Black men. Specific Aims: Aim1: Write a systematic review to synthesize the current literature elucidating the association between BMI, waist circumference (WC), hip circumference (HC), and waist-hip ratio (WHR), and racial disparities in PCa incidence, progression, and mortality. Aim2: Use national-level prospective cohort data to clarify the association between central adiposity and PCa outcomes. Results: Many available PCa reviews focused on BMI’s role in screening disparities. Few explored the role of adiposity in incidence, progression, or mortality disparities. Articles on PCa occurrence and outcomes often did not present race-specific effect estimates. Most adjusted for race in multivariate models. The available evidence suggests a unique role of adiposity-related factors in the risks for PCa occurrence, progression, disparate treatment efficacy, and mortality. Cohort analyses demonstrated an inverse association between WC and PCa incidence, and a positive association with PCa-specific mortality. Larger HC inversely associated with PCa occurrence and positively associated with cause-specific mortality. Additional adjustment for BMI tended to attenuate these findings. No significant association observed for WHR. Conclusion: Clarifying the role of adiposity in PCa disparities will illuminate adiposity-related targets for intervention and further research.