The effect of dutasteride on the usefulness of prostate specific antigen for the diagnosis of high grade and clinically relevant prostate cancer in men with a previous negative biopsy: results from the REDUCE study.

PURPOSE We assessed whether dutasteride enhances the usefulness of total prostate specific antigen for diagnosing clinically significant prostate cancer. MATERIALS AND METHODS The 4-year REDUCE study evaluated the efficacy and safety of 0.5 mg dutasteride daily for prostate cancer risk reduction in men with a prostate specific antigen of 2.5 to 10.0 ng/ml and a negative prostate biopsy. Specificity, sensitivity, and positive and negative predictive values of prostate specific antigen for the diagnosis of prostate cancer were assessed. RESULTS Final prostate specific antigen before biopsy and change from month 6 to final prostate specific antigen performed better for the diagnosis of Gleason score 7-10 tumors in men who received dutasteride vs placebo as assessed by the area under the ROC curves (0.700 vs 0.650, p = 0.0491; and 0.699 vs 0.593, p = 0.0001, respectively). Increases in prostate specific antigen were associated with a higher likelihood of biopsy detectable, Gleason score 7-10 and clinically significant (modified Epstein criteria) prostate cancer. Percentage decreases in prostate specific antigen from baseline to month 6 in the dutasteride arm did not predict prostate cancer overall or Gleason score 7-10 cancer. CONCLUSIONS In men with a previously negative prostate biopsy, prostate specific antigen performed better during the 4-year study as a marker of prostate cancer in men who received dutasteride vs placebo. The degree of prostate specific antigen increase after 6 months was a better indicator of clinically significant cancer in the dutasteride arm than in the placebo arm. Conversely, the initial decrease in prostate specific antigen in men taking dutasteride did not predict the likelihood of prostate cancer.