5α-reductase inhibitors (5-ARIs) are used to treat benign prostatic enlargement, a common condition causing urinary outflow obstruction.1 They also reduce prostate-specific antigen (PSA) by approximately 50%.2 Our group has recently published that among US military veterans, 5-ARIs are associated with delays in prostate cancer (PC) diagnoses, higher grade and stage at presentation, and worse PC-specific mortality (PCSM), presumably because of misinterpreted PSA values.3 We hypothesized that these results are generalizable to the broader US population. Here, KLK3 is linked to prostate cancer.