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-ofstudy 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. Cancer Epidemiol Biomarkers Prev; 25(3); 463-9.