Chronic baseline prostate inflammation is associated with lower tumor volume in men with prostate cancer on repeat biopsy: Results from the REDUCE study

BACKGROUND To evaluate whether baseline acute and chronic prostate inflammation among men with initial negative biopsy for prostate cancer (PC) is associated with PC volume at the 2-year repeat prostate biopsy in a clinical trial with systematic biopsies. METHODS Retrospective analysis of 886 men with negative baseline prostate biopsy and positive 2-year repeat biopsy in the Reduction by Dutasteride of PC Events (REDUCE) study. Acute and chronic inflammation and tumor volume were determined by central pathology. The association of baseline inflammation with 2-year repeat biopsy cancer volume was evaluated with linear and Poisson regressions controlling for demographics and laboratory variables. RESULTS Chronic, acute inflammation, and both were detected in 531 (60%), 12 (1%), and 84 (9%) baseline biopsies, respectively. Acute and chronic inflammation were significantly associated with each other (P-<-0.001). Chronic inflammation was associated with larger prostate (P-<-0.001) and lower pre-repeat biopsy PSA (P-=-0.01). At 2-year biopsy, baseline chronic inflammation was associated with lower mean tumor volume (2.07-μl vs. 3.15-μl; P-=-0.001), number of biopsy cores involved (1.78 vs. 2.19; P-<-0.001), percent of cores involved (17.8% vs. 22.8%; P-<-0.001), core involvement (0.21-μl vs. 0.31-μl; P-<-0.001), and overall percent tumor involvement (1.40% vs. 2.01%; P-<-0.001). Results were unchanged in multivariable analysis. Baseline acute inflammation was not associated with any tumor volume measurement. CONCLUSION In a cohort of men with 2-year repeat prostate biopsy positive for PC after a negative baseline biopsy, baseline chronic inflammation was associated with lower PC volume.