Validation of a nomogram for predicting positive repeat biopsy for prostate cancer.
OBJECTIVE
We reported a nomogram and subsequently a corrected version for predicting the probability of positive biopsy in men with 1 or more prior negative biopsies. In this study we assessed the validity of this nomogram when applied to an external dataset.


METHODS
There were 230 patients from the Brooklyn Veterans Administration Medical Center who underwent 1 or more repeat biopsies after initial negative biopsy from January 1993 to June 2003. Predictor variables studied in the nomogram were patient age, family history of prostate cancer, digital rectal examination, serum prostate specific antigen, prostate specific antigen slope, months from initial negative biopsy session, months from previous negative biopsy session, cumulative number of negative cores previously taken and history of high grade intraepithelial neoplasm or atypical small acinar proliferation. We calculated the nomogram predicted probability in each patient. These predicted outcomes were compared with actual biopsy results. Area under the ROC curve was calculated as a measure of discrimination. Calibration was assessed graphically.


RESULTS
We evaluated a total of 356 repeat biopsies in 230 patients (mean 2.56 total biopsies per patient). The mean number of total cores per patient was 17.9. There were 78 positive biopsies. The area under the ROC curve was 0.71, which was greater than any single risk factor. Nomogram calibration appeared to be good.


CONCLUSIONS
Our corrected nomogram for predicting positive repeat biopsy performed well when applied to a sample of men at the Brooklyn Veterans Administration Medical Center. This nomogram can provide important additional information to aid the urologist and patient with a negative biopsy in evaluating clinical options.
Yanke
Brent V
BV
Department of Urology, State University of New York Downstate Medical Center, Brooklyn, New York, USA.
Gonen
Mithat
M
Scardino
Peter T
PT
Kattan
Michael W
MW
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D049451:Nomograms; D011237:Predictive Value of Tests; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results