Diagnostic significance of reassessment of prostate biopsy specimens by experienced urological pathologists at a high-volume institution.

In prostate cancer, accurate diagnosis and grade group (GG) decision based on biopsy findings are essential for determining treatment strategies. Diagnosis by experienced urological pathologists is recommended; however, their contribution to patient benefits remains unknown. Therefore, we analyzed clinicopathological information to determine the significance of reassessment by experienced urological pathologists at a high-volume institution to identify factors involved in the agreement or disagreement of biopsy and surgical GGs. In total, 1325 prostate adenocarcinomas were analyzed, and the GG was changed in 452/1325 (34.1%) cases (359 cases were upgraded, and 93 cases were downgraded). We compared the highest GG based on biopsy specimens, with the final GG based on surgical specimens of 210 cases. The agreement rate between the surgical GG performed and assessed in our institute and the highest biopsy GG assessed by an outside pathologist was 34.8% (73/210); the agreement rate increased significantly to 50% (105/210) when biopsy specimens were reevaluated in our institute (chi-square test, P < 0.01). Multivariate logistic regression analysis showed that only the length of the lesion in the positive core with the highest GG in the biopsy was a significant factor for determining the agreement between biopsy GG and surgical GG, with an odds ratio of 1.136 (95% confidence interval: 1.057-1.221; P < 0.01). Thus, reassessment by experienced urological pathologists at high-volume institutions improved the agreement rate. However, it should be noted there is a high probability of discordance between a small number of lesions or short lesions and surgical GG.