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

Objective: To investigate the effect on cancer detection by varying the number of cores taken for prostate biopsy according to the size of the prostate.

Patients and methods: 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.

Results: 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.

Conclusions: 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.