Nomograms based on the Tyrol screening data of 2,271 patients to predict prostate cancer biopsy positivity.
203 Background: There are no published nomograms that predict prostate cancer in a screened population. We describe three nomograms that predict for prostate cancer on biopsy derived from a large screening population. Methods: Patients from the Tyrol screening study of known age, total prostate-specific antigen (tPSA), digital rectal examination (DRE), prostate volume, and percent free PSA (%fPSA), and who underwent an initial prostate biopsy from January 1992 to June 2004, were included (n=2271). Multivariable logistic regression models were used to develop the biopsy positivity predictive nomograms: nomogram 1- age, DRE, tPSA; nomogram 2- age, DRE, tPSA, prostate volume; nomogram 3- age, DRE, tPSA, prostate volume, %fPSA. The predictive accuracy of the models was assessed in terms of discrimination and calibration. External validation of the nomograms was performed by comparison with a urologically referred population of patients who underwent prostate biopsy (n=599). Results: All three nomograms discriminated well between biopsy positive and biopsy negative patients for both the screening and urologically referred cohorts (nomogram 3 better than nomogram 2 better than nomogram 1). All three nomograms were well calibrated internally, but the nomograms under-predicted the probability of a positive biopsy in the urologically referred cohort. Conclusions: Our nomogram based on age, total PSA, and DRE has a good predictive ability to differentiate between screened patients that will show cancer on initial prostate biopsy and those that will not. Adding prostate volume and percent free PSA improves this predictive power further. All three nomograms under-predict prostate cancer in a urologically referred cohort. These simple nomograms may be of value in counseling screened men with raised PSA and/or abnormal DRE regarding the need for biopsy. No significant financial relationships to disclose.