Optimizing prostate cancer detection during biopsy by standardizing the amount of tissue examined per core.

Abstract

To investigate the effect on cancer detection by varying the number of cores taken for prostate biopsy according to the size of the prostate. A retrospective review of a prospectively registered prostate biopsy database identified 3040 consecutive patients undergoing prostate biopsy at a Veterans Administration Hospital between 1994 and 2008. Of 2224 biopsies, 681 (31%) were found to have cancer and 1540 (69%) had negative biopsies. Prostate volume to biopsy core ratios (volume/number of cores) were derived and a comparative analysis was performed to determine the impact on cancer detection rates. The median prostate volume was significantly smaller for those patients diagnosed with prostate cancer than for those with negative biopsies (33 vs 43 cc, P= 0.01). The median number of cores was the same for both groups of patients (median 12, P= 0.66). The median transrectal ultrasonography TRUS size/core ratio was 3.5 [interquartile range (IQR) 2.5] for patients with identified cancer as compared with 4.7 (IQR = 3.9) for those with negative biopsies (P= 0.000). On multivariable logistic regression analysis TRUS size/core ratio had a significant impact on cancer detection with a relative risk ratio of 1.29 (95% confidence interval, 1.1-1.5, P= 0.001) even when controlled for age, race, prostate volume, digital rectal examination and prostate-specific antigen level. Prostate cancer detection can be enhanced by individualizing the number of cores performed to a real-time prostate volume sampling. The present study emphasizes that optimal cancer detection rates were observed when a ratio of 3.5 cc per tissue core was achieved. Proper prospectively designed studies must be performed to further validate these findings.