Login to Access Video or Poster Abstract: MP14-09
Sources of Funding: American Institute of Cancer Research, NIH 1K24CA160653, GlaxoSmithKline

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 in prostate cancer risk in 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 (ORs) for associations between region and prostate inflammation, and between region and prostate cancer risk at trial-mandated repeat biopsy. 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; p<0.0001 and OR 2.04; p<0.0001, respectively), while South Americans were less likely to have acute inflammation (OR 0.42; p<0.0001). Among North Americans, Canadians were more likely to have acute prostate inflammation than men from the United States (OR 1.40; p=0.014). Among Europeans, the prevalence of acute inflammation was 15-38% lower in Northern, Southern and Eastern Europe, relative to Western Europe, 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; p=0.180) and Australia/New Zealand (OR 0.48; p=0.036), 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; p=0.016 and OR 1.74; p<0.0001, 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.

Funding

American Institute of Cancer Research, NIH 1K24CA160653, GlaxoSmithKline