Initial extended transrectal prostate biopsy - Are more prostate cancers detected with 18 cores than with 12 cores?

Purpose: We retrospectively investigated the detection rates of prostate cancer, high grade prostatic intraepithelial neoplasia and atypical glands suggestive of carcinoma by initial 18 and 12-core prostate biopsy. Materials and Methods: A total of 3,460 consecutive patients with prostate specific antigen between 2.5 and 15 ng/ml underwent 12 (1,684) or 18 (1,776) core prostate biopsy under local anesthesia at 2 departments that adopted the same indications for performing biopsy. Biopsies were evenly distributed throughout the prostate in 6 sectors. In the 12-core prostate biopsy group 2 samples were obtained from each sector and in the 18-core prostate biopsy group 1 additional core was taken from each sector. Results: The cancer detection rate in patients who underwent 18-core prostate biopsy was not different from the rate in those who underwent 12-core prostate biopsy (39.9% and 38.4%, p = 0.37), nor did the detection of atypical glands suggestive of carcinoma differ significantly between the 2 groups (2.9% and 3.3%, respectively, p = 0.33). However, 18-core prostate biopsy detected a significantly higher percent of cases of high grade prostatic intraepithelial neoplasia (20.0% vs 12.9%, p = 0.001). The cancer detection rate was higher with 18 than with 12-core prostate biopsy in patients with a prostate volume of 55 cc or greater (31.5% vs 24.8%, p = 0.01) but not in those with a prostate volume of less than 55 cc (54.3% and 53.0%, respectively, p = 0.7). Moreover, we determined that patients with positive digital rectal examination findings do not need 18-core prostate biopsy as opposed to 12-core prostate biopsy. Conclusions: Compared with 12-core prostate biopsy, 18-core prostate biopsy detects significantly more cases of high grade prostatic intraepithelial. neoplasia. However, 18-core prostate biopsy detects a significantly higher number of cancer only in patients with a prostate volume of 55 cc or greater. OI Guazzoni, Giorgio Ferruccio/0000-0002-5713-8313