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

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Abstract
Study Type – Diagnostic (exploratory cohort) Level of Evidence 2b What’s known on the subject? and What does the study add? The main goal of a prostate biopsy is to identify clinically relevant prostate cancer with the lowest possible morbidity from the procedure. Over time, many have tried different variations in the procedure in an attempt to find the optimal methodology for performing prostate biopsies. These changes include better equipment in helping optimize cancer localization, varying the number of cores in efforts to improve cancer detection, and sampling various areas of the prostate to find cancer that might be difficult to identify. To our knowledge we are the first to describe performing prostate biopsies by keeping the sampling size constant and varying the number of cores based on the size of the prostate. The study adds a variation in the current techniques used for prostate biopsies. In certain situations, using a standard number of cores makes obtaining proper sampling of a prostate difficult. We propose a methodology in performing prostate biopsies that will allow for standardization of the tissue per core analysed, thus improving the sampling of the prostate. 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.

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