Chronic Baseline Prostate Inflammation is Associated with Lower Tumor Grade in Men with Prostate Cancer on Repeat Biopsy: Results from the REDUCE Study

Purpose:We investigated whether baseline acute or chronic prostate inflammation among men with initial negative biopsies for prostate cancer was associated with cancer grade in 2-year repeat biopsies.Materials and Methods:Retrospective analyses were conducted of 889 men aged 50 to 75 years old with negative baseline prostate biopsy and 2-year repeat biopsy positive for prostate cancer in the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) study. Acute and chronic prostate inflammation and cancer grade were determined by central pathology during the REDUCE study. The association of inflammation in baseline and 2-year repeat biopsy and prostate cancer grade in 2-year repeat biopsy was evaluated with Student's t-test, chi-squared test and multivariable logistic regression.Results:Chronic, acute inflammation and both were detected in 533 (60%), 12 (1%) and 85 (10%) baseline biopsies, respectively. Presence of acute and chronic inflammation were significantly associated with each other (p <0.001). Both types of inflammation were unrelated to race, body mass index, prostate specific antigen or digital rectal exam. At the 2-year biopsy, 621 (70%) tumors were low grade (Gleason scores 2-6) and 268 (30%) were high grade (Gleason scores 7-10). In univariable and multivariable analyses, men with baseline chronic inflammation had significantly fewer high grade tumors (univariable OR 0.64, 95% CI 0.47-0.87, p=0.004; multivariable OR=0.68, 95% CI0.50-0.93, p=0.016) than those without baseline chronic inflammation. Baseline acute inflammation was not associated with tumor grade (univariable OR 0.74, 95% CI 0.45-1.20, p=0.22; multivariable OR 0.78, 95% CI 0.48-1.29, p=0.34).Conclusions:Chronic inflammation in a negative biopsy was associated with lower prostate cancer grade among men with cancer on follow-up 2-year biopsy.