Inflammation in Benign Prostate Tissue and Prostate Cancer in the Finasteride Arm of the Prostate Cancer Prevention Trial.

BACKGROUND A previous analysis of the placebo arm of the Prostate Cancer Prevention Trial (PCPT) reported 82% overall prevalence of intraprostatic inflammation and identified a link between inflammation and higher-grade prostate cancer and serum PSA. Here, we studied these associations in the PCPT finasteride arm. METHODS Prostate cancer cases (N = 197) detected either on a clinically indicated biopsy or on protocol-directed end-of-study biopsy, and frequency-matched controls (N = 248) with no cancer on an end-of-study biopsy were sampled from the finasteride arm. Inflammation in benign prostate tissue was visually assessed using digital images of hematoxylin and eosin-stained sections. Logistic regression was used for statistical analysis. RESULTS In the finasteride arm, 91.6% of prostate cancer cases and 92.4% of controls had at least one biopsy core with inflammation in benign areas (P < 0.001 for difference compared with placebo arm). Overall, the odds of prostate cancer did not differ by prevalence [OR, 0.90; 95% confidence interval (CI), 0.44-1.84] or extent (P trend = 0.68) of inflammation. Inflammation was not associated with higher-grade disease (prevalence: OR, 1.07; 95% CI, 0.43-2.69). Furthermore, mean PSA concentration did not differ by the prevalence or extent of inflammation in either cases or controls. CONCLUSION The prevalence of intraprostatic inflammation was higher in the finasteride than placebo arm of the PCPT, with no association with higher-grade prostate cancer. IMPACT Finasteride may attenuate the association between inflammation and higher-grade prostate cancer. Moreover, the missing link between intraprostatic inflammation and PSA suggests that finasteride may reduce inflammation-associated PSA elevation.