Characteristics of Prostate Cancers Missed by Biopsies: Evaluation of Cumulative Tumor Volume Missed According to Cancer True Prevalence

Purpose: To characterize missed prostate tumors and their cumulative volume with various biopsy regimens to determine optimal biopsy schemes. Methods: We performed 6, 12 and 18-core needle biopsies on 165 and 36-core biopsies on 47 autopsy prostates, respectively. The 6-core biopsy included 6 cores from the mid peripheral zone (MPZ), the 12-core biopsy included 6 cores from the MPZ and lateral PZ (LPZ), and the 18-core biopsies included 6 cores from the MPZ, LPZ and central zone (CZ). The 36-core biopsies included 12 cores in each of these 3 areas. We analyzed the sensitivity of biopsies at each site and evaluated the cumulative volume of cancers and tumor foci missed. Results: Whole-mount analysis identified 59 cancers, 110 tumor foci, and a total cumulative tumor volume of 43 cm. The percentage of tumor foci and corresponding cumulative volume missed with 6, 12, 18 and 36-core biopsies were of 79% and 58%, 64% and 48%, 57% and 26%, and 42% and 17%, respectively (p < 0.05). 12-core biopsies from the MPZ and LPZ performed best for clinically significant cancers detection. However, increasing the number of cores over the 6-core biopsy cutoff increased solely the detection of tumor foci < 0.5 cm. Conclusion: Twelve biopsies from the MPZ and LPZ detected most of the clinically significant cancers while missing most of the tumor foci. These missed tumors represented only a small amount of the overall cancer volume.