[Analysis of transrectal needle biopsy of the prostate: usefulness of systematic 12 core biopsy].

A total of 978 of transrectal prostate biopsies performed between January 1998 and December 2005 at Ikeda Municipal Hospital were reviewed to determine the usefulness of the systematic 12 core biopsy including the apex and transition zone (TZ). Prostate cancer was detected in 531 of the 978 cases (54.3%). The systematic 6 core biopsy was performed between 1998 and 2000. In this group the cancer detection rate was 40.8% (87 out of 213 cases). In the systematic 12 core biopsy group since 2001 the cancer detection rate was 58.0% (444 out of 765 cases). The cancer detection ratio in the systematic 12 core biopsy group was significantly higher than that in the 6 core group (p<0.0001). In the subgroup whose prostate-specific antigen (PSA) value was in the gray zone (4. 1-10.0 ng/ml), the cancer detection rate was 22.9% (25 of 109 cases) in the systematic 6 core biopsy group and 45.7% (186 of 407 cases) in the systematic 12 core biopsy group. Of the 444 cases diagnosed as having prostate cancer by the systematic 12 core biopsy, 64 cases (14.4%) had positive cores only in additional cores from the apex and TZ. Our study revealed that the systematic 12 core prostate biopsy including the apex and TZ was useful for improving the cancer detection ratio of the prostate.