Impact of prostate biopsy secondary pathology review on radiotherapy management

Background: The Gleason scoring system is the most widely used method to assess prostate adenocarcinoma pathology however interobserver variability is significant. Gleason score, PSA level, and clinical stage comprise the NCCN risk stratification that guides treatment decision making. Given the importance of an accurate Gleason score and wide interobserver variability, referral centers routinely review outside pathology at the time of consultation. We sought to address the impact a secondary pathology review had on radiation therapy treatment recommendations in men with prostate cancer at our institution. Methods: We retrospectively collected patient data on 342 patients seen at our institution from January 2012 to December 2018. Clinicopathologic data were used to subdivide patients into risk groups and available treatment options per NCCN criteria. Cases reviewed by our genitourinary pathologist (GUP) were compared with reports from outside pathologists. Inter-rater reliability between pathologists was assessed with weighted Cohen's kappa statistic and agreement of treatment options was determined by McNemar's exact tests. Results: GUP scored more cores positive in 16.47% of cases on secondary review. Primary Gleason score was changed in 12.28% of patients and secondary score in 26.02% of cases. Total Gleason score was different in 29.24% of cases, 19.01% were downgraded and 10.23% upgraded. The weighted kappa statistic was 0.759 (95% confidence interval [CI]: 0.711, 0.807). 18.77% of patients were assigned to a different NCCN risk group following secondary review. The weighted kappa statistic comparing NCCN risk stratification was 0.802 (95% CI: 0.754, 0.850). Secondary review influenced radiation therapy recommendations pertaining to brachytherapy boost and androgen deprivation therapy in men with high risk disease (χ² = 5.33, p = 0.0386; χ² = 8.05, p = 0.0072, respectively). Kappa statistic was found to be highest when GUP assessed high-risk disease versus all other categories (κ = 0.823, 95% CI: 0.750, 0.895). Conclusions: We found nearly one in five men (18.7%) was assigned a different NCCN risk group and thus offered potentially different treatment options after a secondary pathology review at our institution. Given the inherent nature of prostate cancer and lung disease-specific survival associated with modern therapies, our study demonstrates the importance of a secondary pathology review and its potential impact on radiation therapy recommendations.