Transrectal ultrasound-guided prostate rebiopsy: How many core sampling should be applied to which patient?

Background: We investigated the correlation between the sampled number of cores in rebiopsy and the cancer detection rate (CDR). Materials and Methods: Two hundred and twelve patients with normal rectal examination who had undergone rebiopsy in the past 5 years were examined retrospectively. Moreover, 68% of them had undergone 12 cores (Group 1) while 32% had undergone 20 cores (Group 2). Both groups were compared with respect to the CDR. Results: There was no difference between groups in terms of age, total prostate-specific antigen, and prostate volume (P > 0.05). Forty-one (19%) of 212 patients were diagnosed with cancer, and the CDR was significantly higher in Group 2 (30.9% vs. 13.9%, P = 0.004). This rate increased from 6.5% to 20% (P = 0.025) and from 0% to 33.3% (P = 0.023), respectively, with 12-core and 20-core rebiopsies in patients whose initial pathology indicated benign and high-grade prostatic intraepithelial neoplasia (HGPIN). Furthermore, cancer was detected in 24 (40%) of 60 patients who were diagnosed with atypical small acinar proliferation (ASAP) in the initial biopsy. However, despite being higher in 20-core biopsy group (47.6% vs. 35.9%), this was not statistically significant (P = 0.377). Conclusions: At least 20 cores should be sampled in rebiopsy, especially in the patients diagnosed with benign and HGPIN. However, we believe that standard systematic sampling will be sufficient for the patients diagnosed with ASAP.