Nomogram to predict prostate cancer diagnosis on primary transrectal ultrasound-guided prostate biopsy in a contemporary series.

OBJECTIVE

Transrectal ultrasound-guided biopsy (TRUSB) remains the mainstay for prostate cancer (CaP) diagnosis. Numerous variables have shown associations with development of CaP. We present a nomogram that predicts the probability of detecting CaP on TRUSB.

METHODS

After obtaining institutional review board approval, all patients undergoing primary TRUSB for CaP detection at a single center at our institution between 2/2000 and 9/2007 were reviewed. Patients undergoing repeat biopsies were excluded, and only the first biopsy was included in the analysis. Variables included age at biopsy, race, clinical stage, prostate specific antigen (PSA), number of cores removed, TRUS prostate volume (TRUSPV), body mass index, family history of CaP, and pathology results. S-PLUS 2000 statistical software was utilized with p < 0.05 considered significant. Cox proportional hazards regression models with restricted cubic splines were utilized to construct the nomogram. Validation utilized bootstrapping, and the concordance index was calculated based on these predictions.

RESULTS

A total of 1,542 consecutive patients underwent primary TRUSB with a median age of 64.2 years (range 34.9-89.2 years), PSA of 5.7 ng/ml (range 0.3-3,900 ng/ml), number of cores removed of 8.0 (range 1- 22) and TRUSPV of 36.4 cm(3) (range 9.6-212.0 cm(3)). CaP was diagnosed in 561 (36.4%) patients. A nomogram was constructed incorporating age at biopsy, race, PSA, body mass index, clinical stage, TRUSPV, number of cores removed, and family history of CaP. The concordance index when validated internally was 0.802.

CONCLUSIONS

We have developed and internally validated a model predicting cancer detection in men undergoing TRUSB in a contemporary series. This model may assist clinicians in risk-stratifying potential candidates for TRUSB, potentially avoiding unnecessary or low-probability TRUSB.