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

Abstract

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. 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. 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%. 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.