Abstract 4962: Geographic disparities in prevalence of baseline prostate inflammation and prostate cancer risk: Results from a multinational trial
Authors: Allott Emma H. , Markt Sarah , Howard Lauren E. , Vidal Adriana C. , Moreira Daniel M. , Castro-Santamaria Ramiro , Andriole Gerald L. , Mucci Lorelei A. , Freedland Stephen J. 
Published: July 2017

Introduction: Prostate cancer incidence rates vary 25-fold worldwide. The distribution of lifestyle factors also varies by geographic region and these factors may impact prostate inflammation, which is inversely associated with prostate cancer risk in the REduction by DUtasteride of prostate Cancer Events (REDUCE) trial. Herein, we examined geographic differences in the prevalence of histological prostate inflammation and geographic differences in prostate cancer risk using REDUCE, a multinational trial of men with a negative baseline prostate biopsy.

Methods: We conducted a retrospective analysis of data from 7,213 men with a negative baseline prostate biopsy in REDUCE from Europe (n=4,802), North America (n=1,796), South America (n=467), and Australia/New Zealand (n=148). Histological inflammation was classified as chronic (lymphocytes, macrophages) or acute (neutrophils) by central review of negative baseline prostate biopsies. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI) for associations between geographic region and prostate inflammation, and between geographic region and prostate cancer risk at trial-mandated repeat biopsy, adjusting for potential confounders. To avoid confounding by race, analyses were restricted to white men.

Results: Chronic and acute prostate inflammation was detected in 77% and 15% of men, respectively. Relative to Europeans, North Americans and Australians/New Zealanders were more likely to have acute prostate inflammation in the negative biopsy (OR 1.74; 95% CI 1.48-2.05 and OR 2.04; 95% CI 1.38-3.02, respectively), while South Americans were less likely to have acute inflammation (OR 0.42; 95% CI 0.28-0.61). Among North Americans, Canadians were more likely to have acute prostate inflammation than men from the United States (OR 1.40; 95% CI 1.07-1.83). Among Europeans, the prevalence of acute inflammation was lower in Northern, Southern and Eastern Europe, relative to Western Europe (OR 0.79; 95% CI 0.65-0.97, OR 0.84; 95% CI 0.66-1.07 and OR 0.62; 95% CI 0.45-0.87, respectively), with similar results for chronic inflammation. Regions with higher prevalence of prostate inflammation had lower prostate cancer risk at 2-year biopsy, including North America (OR 0.87; 95% CI 0.71-1.07) and Australia/New Zealand (OR 0.48; 95% CI 0.24-0.95), relative to Europe. Conversely, regions with lower prevalence of prostate inflammation had higher prostate cancer risk at 2-year biopsy, including Northern and Eastern Europe (OR 1.30; 95% CI 1.05-1.62 and OR 1.74; 95% CI 1.29-2.35, respectively), relative to Western Europe.

Conclusions: Geographic disparities in the prevalence of prostate inflammation is a potential biologic mechanism contributing to global differences in prostate cancer incidence rates.

Citation Format: Emma H. Allott, Sarah Markt, Lauren E. Howard, Adriana C. Vidal, Daniel M. Moreira, Ramiro Castro-Santamaria, Gerald L. Andriole, Lorelei A. Mucci, Stephen J. Freedland. Geographic disparities in prevalence of baseline prostate inflammation and prostate cancer risk: Results from a multinational trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4962. doi:10.1158/1538-7445.AM2017-4962