PCA3-based nomogram for predicting prostate cancer and high grade cancer on initial transrectal guided biopsy

BACKGROUNDTo develop a validated prostate cancer antigen 3 (PCA3) based nomogram that predicts likelihood of overall prostate cancer (PCa) and intermediate/high grade prostate cancer (HGPCa) in men pursuing initial transrectal prostate biopsy (TRUS-PBx). METHODSData were collected on 3,675 men with serum prostate specific antigen level (PSA) 20ng/ml who underwent initial prostate biopsy with at least 10 cores sampling at time of the biopsy. Two logistic regression models were constructed to predict overall PCa and HGPCa incorporating age, race, family history (FH) of PCa, PSA at diagnosis, PCA3, total prostate volume (TPV), and digital rectal exam (DRE). RESULTSOne thousand six hundred twenty (44%) patients had biopsy confirmed PCa with 701 men (19.1%) showing HGPCa. Statistically significant predictors of overall PCa were age (P<0.0001, OR. 1.51), PSA at diagnosis (P<0.0001, OR.1.95), PCA3 (P<0.0001, OR.3.06), TPV (P<0.0001, OR.0.47), FH (P=0.003, OR.1.32), and abnormal DRE (P=0.001, OR. 1.32). While for HGPCa, predictors were age (P<0.0001, OR.1.77), PSA (P<0.0001, OR.2.73), PCA3 (P<0.0001, OR.2.26), TPV (P<0.0001, OR.0.4), and DRE (P<0.0001, OR.1.53). Two nomograms were reconstructed for predicted overall PCa probability at time of initial biopsy with a concordance index of 0.742 (Fig. 1), and HGPCa with a concordance index of 0.768 (Fig. 2). CONCLUSIONSOur internally validated initial biopsy PCA3 based nomogram is reconstructed based on a large dataset. The c-index indicates high predictive accuracy, especially for high grade PCa and improves the ability to predict biopsy outcomes. Prostate 75:1951-1957, 2015. (c) 2015 Wiley Periodicals, Inc.