Laterally directed biopsies detect more clinically threatening prostate cancer: computer simulated results.
BACKGROUND: The purpose of this study was to determine, whether a modified fan-shaped biopsy (MFSB) technique which utilizes six laterally directed biopsies would lead to higher detection rates of clinically threatening prostatic carcinoma than the six random systematic core biopsy (SRSCB) method. METHODS: We reconstructed 3-dimensional solid computer models of 86 autopsy prostates and 40 radical prostatatectomy specimens. Simulations of SRSCB and MFSB were then performed using the same biopsy sites except that the biopsy probe was rotated 45 degrees toward posterolateral peripheral zone for MFSB. When the Gleason sum was less than 7, clinically threatening cancers were defined as having a tumor volume > or =0.25 cc or > or =0.5 cc. RESULTS: When the cut off volume was 0.25 cc, MFSB detected significantly more threatening carcinomas in autopsy prostates than did SRSCB (P < 0.0082). This was also true for the surgical prostates (P < 0.0047) as well as for a sub-group of non-palpable carcinomas (P < 0.0047). When the cut off volume was increased to 0.5 cc, MFSB detected significantly more threatening carcinomas in the radical series (P < 0.0047) and for the non-palpable carcinomas (P < 0.0082), but not in the autopsy series. CONCLUSIONS: The MFSB technique, which utilizes laterally directed biopsies, appears to be an effective approach to improve the detection of clinically threatening prostatic carcinoma.