A novel repeat biopsy nomogram based on three-dimensional extended biopsy.

Objectives: To develop a nomogram based on a cohort examined with 3-dimensional (3D) protocol for diagnosis of prostate cancer on repeat biopsy.

Methods: Of 4074 consecutive men undergoing prostate biopsy at our institutions between 2000 and 2009, 775 men with at least 1 previous negative biopsy underwent repeat biopsy with a 3D protocol. Men with previous atypical glands or atypical small acinar proliferation and/or without available prostate-specific antigen (PSA) kinetics information were excluded. The remaining 515 men constituted the study cohort. We developed a logistic regression-based nomogram with 70% of the cohort selected randomly; we validated it with the remaining 30%. Predictive accuracy and performance characteristics were assessed using the area under the receiver operating characteristic curve (AUC) and calibration plots, respectively. The threshold probability was evaluated with decision curve analysis.

Results: We developed a novel repeat biopsy nomogram incorporating age, free to total PSA ratio, prostate volume, history of previous extended biopsy, and PSA doubling time. Validation confirmed predictive accuracy with an AUC value of 0.791. Calibration plots showed good agreement. The decision curve of the nomogram was superior to the decision curve of biopsying all men in a range of threshold probability over 0.15. At the threshold of 0.2, the number of unnecessary biopsies could be reduced by 10 per 100, without missing prostate cancer.

Conclusions: We developed a novel repeat biopsy nomogram based on a cohort examined with 3D protocol. This repeat biopsy nomogram is clinically beneficial, preventing a substantial number of unnecessary biopsies.