Saturation biopsies on autopsied prostates for detecting and characterizing prostate cancer

To evaluate a 36-core saturation biopsy scheme on autopsied prostate glands to estimate the detection rate based on the true cancer prevalence, and to compare the cancer features on biopsy with whole-mount pathological analysis, as saturation biopsies have been proposed as a tool to increase the prostate cancer detection rate, and as a staging tool to identify potentially insignificant cancers before surgery. We took 36-core needle biopsies in 48 autopsied prostates from men who had no history of prostate cancer. The first 18 cores corresponded to an extended biopsy protocol including six cores each in the mid peripheral zone (PZ), lateral PZ and central zone. Six additional cores were then taken in each of these three locations. We compared the histological characteristics of step-sectioned prostates with the biopsy findings. Tumours were considered clinically insignificant if they were organ-confined with an index tumour volume of < 0.5 mL and Gleason score of <= 6. The pathological evaluation identified 12 (25%) cases of prostate cancer and 22 tumour foci; seven prostate cancers were significant. Of the 22 tumour foci, 16 (73%) were in the PZ. The first 18 cores detected seven cancers (58%), of which five were clinically significant. The last 18 cores detected four cancers, all of which were already detected by the first 18 cores. Of the five cancers remaining undetected by biopsies, two were clinically significant and three were insignificant. Comparison of the histological characteristics between biopsies and step-sectioned prostates showed an overestimation of Gleason score by saturation biopsies in three of seven cases. The evaluation of saturation biopsies based on the true prevalence of prostate cancer showed no increase in detection rate over a less extensive 18-core biopsy. Also, saturation biopsies might overestimate the final Gleason score on whole-mount analysis.