Baseline Prostate Atrophy is Associated with Reduced Risk of Prostate Cancer in Men Undergoing Repeat Prostate Biopsy

Purpose We evaluated whether the presence and severity of baseline prostate atrophy in men with initial biopsy negative for prostate cancer was associated the risk of subsequent prostate cancer detection in a clinical trial with scheduled study mandated biopsies. Materials and Methods We retrospectively analyzed the records of 3,084 men 50 to 75 years old with prostate specific antigen between 2.5 and 10 ng/ml, and a prior negative biopsy in the placebo arm of the REDUCE (Reduction by Dutasteride of Prostate Cancer Events) study who completed at least 1 per-protocol biopsy. Prostate cancer (defined as present or absent) and prostate atrophy (graded as absent, mild or moderate/marked) was assessed by central pathology review. The association of baseline atrophy with positive 2 and 4-year repeat biopsies was evaluated with logistic regression, controlling for baseline covariates. Results Baseline prostate atrophy was detected in 2,143 men (70%) and graded as mild and moderate/marked in 1,843 (60%) and 300 (10%) baseline biopsies, respectively. Patients with atrophy were older and had a larger prostate, and more acute and chronic prostate inflammation. At 2-year biopsy the prostate cancer incidence was 17% (508 cases). Baseline atrophy was significantly associated with lower prostate cancer risk (univariable and multivariable OR 0.60, 95% CI 0.50-0.74 and OR 0.67, 95% CI 0.54-0.83, p <0.001, respectively) at the 2-year biopsy. These results were similar at the 4-year biopsy (univariable and multivariable OR 0.70, 95% CI 0.53-0.93 and OR 0.72, 95% CI 0.53-0.97, p = 0.03, respectively). Relative to no atrophy the prostate cancer risk at the 2-year repeat biopsy was lower for mild atrophy (OR 0.69, 95% CI 0.55-0.86) and moderate/marked atrophy (OR 0.51, 95% CI 0.34-0.76, each p <0.001). Conclusions Baseline prostate atrophy in men with a prostate biopsy negative for prostate cancer was independently associated with subsequent lower prostate cancer detection.