371 ARE GENETIC VARIANTS THAT PROMOTE PSA EXPRESSION ASSOCIATED WITH MORE FAVORABLE PATHOLOGIC TUMOR FEATURES

Abstract

cohort of 434 patients with a total PSA 50 ng/mL who were referred to our institution for an initial prostate biopsy. Outpatient transrectal ultrasound-guided prostate biopsies were performed according to a standardized institutional saturation scheme (18-22 cores). Logistic regression models were fitted to test the predictors of PCa at initial biopsy. Predictive accuracy estimates of biopsy outcome predictions were quantified using the area under the receiver-operating characteristic curve (AUC). Differences in AUCs were tested using the DeLong method. Regression coefficients were used to create a nomogram that was internally validated using 200 bootstrap resamples. Finally, the extent of overestimation or underestimation of the observed PCa rate at biopsy was determined with calibration plots. RESULTS: Overall, 179 (41.2%) patients were diagnosed with PCa at initial extended prostate biopsy. In accuracy analyses, PHI emerged as the most informative independent predictor of PCa (AUC: 74.5%; p 0.001). The inclusion of PHI to a multivariable logistic regression model based on established predictors of PCa (age and digital rectal examination) significantly increased the predictive accuracy of a 3.4% extent (from 75.6 to 79.0%; p 0.001). Calibration of the nomogram was good within the whole range of predicted probabilities. CONCLUSIONS: We developed a nomogram based on PHI that can assist clinicians in the decision to biopsy by giving patients an individual risk of PCa. While internal validation provided evidences of good calibration and accuracy of the tool, external validation of our findings is still required.