How many cores should be taken in a repeat biopsy on patients in whom atypical small acinar proliferation has been identified in an initial transrectal prostate biopsy?

OBJECTIVE To compare cancer detection rates according to the number of biopsy cores in patients on whom a repeat prostate biopsy was performed for atypical small acinar proliferation (ASAP). MATERIALS AND METHODS The data of 4950 consecutive patients on whom prostate biopsies were performed were assessed retrospectively. A total of 107 patients were identified as having ASAP following an initial prostate biopsy, and they were included in the study. A six-core prostate biopsy (PBx) was performed on 15 of the 107 patients, 12 PBx on 32 patients, and 20 PBx on 60 patients. Cancer detection rates were compared according to the number of biopsy cores. The localization of the cancer foci was also evaluated. RESULTS The cancer detection rates in patients on whom 6 PBx, 12 PBx, and 20 PBx were performed were 20% (3/15), 31% (10/32), and 58% (35/60), respectively, and a statistically significant difference was found (p = 0.005). When cancer detection rates in patients with total prostate specific antigen (PSA) < 10ng/mL, PSA density ≥ 0.15, normal digital rectal examination, and prostate volume ≥ 55mL were compared according to the number of biopsy cores, a significant difference was identified (p = 0.02, 0.03, 0.006, and 0.04, respectively). Seventy-five percent of the foci where cancer was detected were at the same and/or adjacent sites as the ASAP foci in the initial biopsy, and 54% were identified in contralateral biopsies in which ASAP foci were present. CONCLUSION As the biopsy core number increases, the cancer detection rate increases significantly in patients on whom a repeat biopsy is performed due to ASAP. The highest cancer rate is found in 20-core repeat biopsies performed equally from all foci.