- In this study, we tried to design a scheme for performing transrectal ultrasonographic (TRUS)-biopsies that would be accurate and include the optimal number of cores. We included in this study 600 consecutive patients with suspicious findings on a per-rectum examination and/or an elevated prostate-specific antigen (PSA) (>4 ng/mL) level. Patients were followed for 7 to 10 years. In all patients, we took from 8 to 16 biopsy samples, according to the prostate volume, from the lateral aspects. In the second session, the biopsy samples were taken medially; in the third session, we included the transitional zone, while in consecutive sessions, we increased the number of cores from all areas. Only 573 of the patients remained in follow-up. TRUS-biopsy detected prostate cancer (PCa) in 257 patients (44.85% overall detection rate). The detection rate in the first and second sessions was 32.98% and 14.94%, respectively, reaching 13.2% and 2.17%, in the third and fourth sessions, respectively. Prostate volumes were significantly smaller (52.9 +/- 22.4 cc vs 58.9 +/- 23.8 cc, P < 0.002) and the PSA/adenoma/prostate volumes ratio (ad-pro) ratio was higher (18.3 +/- 9 vs 13.96, P < 0/001) in the patients with PCa. Patients with PCa underwent fewer biopsy procedures and biopsy sessions than patients without a diagnosis of PCa (14.9 +/- 8.9 vs 20.4 +/- 12, P < 0.001;1.3 +/- 0.6 vs 1.7 +/- 0.9, P < 0.001). Biopsy samples obtained from the base were positive for cancer only in larger prostates with a mean volume of 54.3 +/- 15.3 cc. Numbers of biopsy procedures and PSA/ad-pro ratio were the strongest predictive factors for PCa detection (P < 0.001). In patients with a prostate volume >or=53 cc and PSA/ad-pro ratio >or=18, the optimal biopsy cores should be >or=15. Using this scheme, the discontinuation of biopsy procedures might be considered after three consecutive sessions.