Purpose: We evaluated the association between the number of biopsy cores revealing high grade prostatic intraepithelial neoplasia and prostate cancer in an era of extended biopsy protocol.
Materials and methods: From December 2004 to September 2007 patients referred to our clinic with a prostate specific antigen of 4 ng/ml or greater or an abnormal digital rectal examination were scheduled for transrectal ultrasound prostatic biopsy with a 12-core template. In patients with high grade prostatic intraepithelial neoplasia we proposed a second prostate specific antigen evaluation and a new 12-core biopsy after 6 months independent of prostate specific antigen. Nonparametric tests were applied for statistical analysis.
Results: We evaluated 650 patients. Of the 147 patients (22%) with high grade prostatic intraepithelial neoplasia 117 underwent a second biopsy 6 months later. Patient characteristics (age, prostate specific antigen, free-to-total prostate specific antigen ratio, prostate volume, prostate specific antigen density) were similar at initial and repeat biopsy. On second biopsy 22 patients (18.8%) presented with prostate cancer (14 with Gleason score 6, 7 with Gleason score 7 and 1 with a Gleason score 8), 75 showed isolated high grade prostatic intraepithelial neoplasia (64.2%) and 20 (17%) had chronic prostatitis. The number of cores (4 or more) involved with high grade prostatic intraepithelial neoplasia on the first biopsy was significantly associated with prostate cancer on the second biopsy (p = 0.001). Prostate specific antigen could not be used to distinguish prostate cancer from benign disease or high grade prostatic intraepithelial neoplasia.
Conclusions: The number of cores with high grade prostatic intraepithelial neoplasia seems to be associated with the presence of cancer on second biopsy. A 6-month biopsy is recommended in patients with high grade prostatic intraepithelial neoplasia when 4 or more cores with high grade prostatic intraepithelial neoplasia are detected in the initial biopsy sample independent of prostate specific antigen.