A Prospective Study of Chronic Inflammation in Benign Prostate Tissue and Risk of Prostate Cancer: Linked PCPT and SELECT Cohorts

Background: We leveraged two trials to test the hypothesis of an inflammation-prostate cancer link prospectively in men without indication for biopsy.Methods: Prostate Cancer Prevention Trial (PCPT) participants who had an end-of-study biopsy performed per protocol that was negative for cancer and who subsequently enrolled in the Selenium and Vitamin E Cancer Prevention Trial (SELECT) were eligible. We selected all 100 cases and sampled 200 frequency-matched controls and used PCPT end-of-study biopsies as "baseline." Five men with PSA > 4 ng/mL at end-of-study biopsy were excluded. Tissue was located for 92 cases and 193 controls. We visually assessed inflammation in benign tissue. We estimated ORs and 95% confidence intervals (CI) using logistic regression adjusting for age and race.Results: Mean time between biopsy and diagnosis was 5.9 years. In men previously in the PCPT placebo arm, 78.1% of cases (N = 41) and 68.2% of controls (N = 85) had at least one baseline biopsy core (∼5 evaluated per man) with inflammation. The odds of prostate cancer (N = 41 cases) appeared to increase with increasing mean percentage of tissue area with inflammation, a trend that was statistically significant for Gleason sum <4+3 disease (N = 31 cases; vs. 0%, >0-<1.8% OR = 1.70, 1.8-<5.0% OR = 2.39, ≥5% OR = 3.31, P_trend = 0.047). In men previously in the finasteride arm, prevalence of inflammation did not differ between cases (76.5%; N = 51) and controls (75.0%; N = 108).Conclusions: Benign tissue inflammation was positively associated with prostate cancer.Impact: This first prospective study of men without biopsy indication supports the hypothesis that inflammation influences prostate cancer development. Cancer Epidemiol Biomarkers Prev; 26(10); 1549-57. ©2017 AACR.