Predictors of prostate cancer on extended biopsy in patients with high-grade prostatic intraepithelial neoplasia: a multivariate analysis model

OBJECTIVE: To define the importance of extended biopsy in patients with high-grade prostatic intraepithelial neoplasia (HGPIN) and to define predictors of cancer in extended biopsy in patients with HGPIN, using multivariate analysis. PATIENTS AND METHODS: In all, 83 patients with previous sextant biopsy of HGPIN had an extended 11-core biopsy taken. Patients with a negative biopsy for cancer were followed by serum prostate-specific antigen (PSA) and digital rectal examination (DRE) every 6 months. The extended biopsy was repeated in 21 patients. The criteria for second biopsy were an increase in PSA and/or abnormal changes on DRE. Overall, 49 patients had a transurethral resection of the prostate (TURP). The cancer-detection rate on extended biopsy was correlated with risk factors using the chi-square test and multivariate analysis. RESULTS: Extended biopsy detected prostate cancer in 30 of the 83 men (36%), with positive cores in only 20 sextant biopsy sites (67%), in only seven in additional sites (23%), and both in three (10%). Of the 21 patients who had repeat extended biopsy, four (19%) had cancers. There were two carcinomas in the 49 TURP specimens (4%). The PSA level, DRE and transrectal ultrasonography findings were not predictive of cancer in extended biopsies (chi-square test). Patient age, PSA density and the number of cores with HGPIN (all P < 0.001) had a significant effect on the cancer-detection rate, and multivariate analysis showed that all three were independent predictors of cancer. A logistic regression model was designed to predict the probability of cancer in extended biopsy, with an overall accuracy of 78%. CONCLUSION: Extended biopsy improved the cancer detection rate by 23% in patients with HGPIN. Patient age, PSA density and the number of cores with HGPIN were the only independent predictors of cancer.