Monofocal and plurifocal high-grade prostatic intraepithelial neoplasia on extended prostate biopsies: factors predicting cancer detection on extended repeat biopsy

Abstract

Objectives To evaluate factors predicting cancer detection by extended repeat prostate biopsies in patients with an initial, isolated, monofocal or plurifocal, high-grade prostatic intraepithelial neoplasia (HGPIN) diagnosis. Methods From 1995 to 2002, after a first set of 10 to 12 systematic biopsy cores, 47 patients with an initial HGPIN diagnosis underwent repeat biopsy using the same technique (mean repeat biopsy cores 11.5) after a median follow-up of 11.4 months (range 3 to 24). Results Cancer was detected at the second biopsy in 21 patients (44.6%). Cancer detection was significantly greater in patients with plurifocal HGPIN than in those with monofocal HGPIN (70% vs. 10%, respectively; P <0.005) and in patients who underwent repeat biopsy more than 6 months after the first biopsy set (65%) compared with patients who underwent repeat biopsy within 6 months (25%; P <0.01; mean follow-up 15.5 and 3.8 months, respectively). Multivariate analysis showed that prostate-specific antigen, prostate-specific antigen density, digital rectal examination, and transrectal ultrasound findings were not statistically significant predictors of prostate cancer, and HGPIN multifocality and interval between biopsies (more than a 6-month follow-up interval) were independent prognostic factors (odds ratio 4.65 and 2.65, respectively). After radical prostatectomy (14 patients), no statistically significant differences were found in the pathologic stage between patient groups stratified by repeat biopsy interval (within or after 6 months). Conclusions After a 10 to 12-core biopsy, patients with initial, isolated monofocal or plurifocal HGPIN diagnoses had an overall cancer detection rate of 45% on repeat extended biopsies. Plurifocal HGPIN on the first biopsy set was the strongest independent predictive factor in cancer detection. A 12 to 18-month interval before repeat biopsy could permit a significantly greater cancer detection rate, with no apparent likelihood of clinical cancer progression.