Background:To evaluate whether the presence of both prostate atrophy (PA) and chronic prostate inflammation (CPI) in the same biopsy and in the same biopsy core are associated with prostate cancer (PCa) risk and grade in repeat biopsies.Methods:Retrospective analyses of 6132 men who were 50-75 years old undergoing 2-year repeat prostate biopsy after a negative baseline biopsy for PCa in the REduction by DUtasteride of prostate Cancer Events (REDUCE) study. PA, CPI and PCa were determined by central pathology. The association of baseline PA and CPI with 2-year repeat biopsy cancer status and grade was evaluated with Ï ‡ 2 test and logistic regression controlling clinicopathological features.Results:PA, CPI and both were detected in 583 (9.5%), 1063 (17.4%) and 3675 (59.9%) baseline biopsies, respectively. Compared with biopsies with neither PA nor CPI, the presence of PA (odds ratio (OR)=0.73, 95% confidence interval (CI)=0.57-0.93), CPI (OR=0.72, 95% CI=0.58-0.88) and both (OR=0.54, 95% CI=0.45-0.64) were associated with lower PCa risk in the 2-year repeat prostate biopsy. Results were similar in multivariable analysis. Among subjects with both PA and CPI, those with both findings in the same core had even lower PCa risk compared with PA and CPI in different cores (univariable OR=0.68, 95% CI=0.51-0.91; multivariable OR=0.73, 95% CI=0.54-0.99). Combination of PA and CPI was associated with lower risk of high-grade PCa.Conclusions:The presence of both PA and CPI in baseline biopsies, especially in the same core, was associated with lower PCa risk and grade. The presence and topographical distribution of PA and CPI may be used in PCa risk stratification.