Relative Contribution of Sampling and Grading to the Quality of Prostate Biopsy: Results from a Single High-volume Institution

Background: The quality of prostate biopsy is affected by sampling (does the urologist take cores from the right place?) and the histological evaluation (does the pathologist grade correctly?).

Objective: To evaluate the relative contribution of sampling and histological evaluation to the reliability of prostate biopsy in terms of concordance with grading of the surgical specimen.

Design, setting, and participants: We identified 848 prostate cancer patients who underwent radical prostatectomy between 2015 and 2017 at our institution with external or internal biopsies. Since 2016, a dedicated uropathologist has reviewed all the biopsies sampled externally.

Outcome measurements and statistical analysis: We considered the discordance between biopsy and final pathology as a proxy for the quality of prostate biopsy, and calculated the corresponding discordance rate for each biopsy setting.

Results and limitations: We observed the highest rate of grade discordance for patients who had an external biopsy without internal review (66%). Biopsies both sampled and reviewed internally had the lowest discrepancy rate (39%; p<0.0001 compared to external biopsies). Biopsies sampled outside our institution and reviewed internally had an intermediate discordance rate (51%; p=0.003).

Conclusions: The quality of prostate biopsy is influenced by both sampling and evaluation. Highly experienced pathological evaluation of needle biopsies is crucial, but biopsy quality also strongly depends on the quality of the sampled material. Future studies should investigate the mechanism underlying discordance in sampling. Consideration should be given to regionalization of prostate biopsy.

Patient summary: The quality of prostate biopsy varies between specialist and community centers. We found that this variation is affected by both sampling (does the urologist take cores from the right place?) and histological evaluation (does the pathologist grade correctly?).