Survival outcomes for adjuvant or salvage radiation in men with pN+M0 prostate cancer.

Abstract

276 Background: The benefit of adjuvant or salvage radiation in pN+ men following radical prostatectomy (RP) is debated. Prior outcome studies are hampered either by missing prognostic variables or poor statistical analysis. We performed a rigorous outcome analysis in completely pathologically staged pN+ men treated with radical prostatectomy at the Univ. of Utah between the years 1998 and 2018. Methods: Men who were cN0M0 prior to surgery found with pN+ disease after RP were identified in our combined prospectively and retrospectively gathered institutional database. Those with metastasis found within 3 months of RP were excluded. The pathologic T and N stage, margin status, # of nodes resected, # of nodes positive, age, and NCI comorbidity scores were known for all subjects. Propensity weighted adjustment for the aforementioned covariates was performed to balance prognostic covariates in those who received EBRT + ADT (RT) versus those who didn’t (No-RT). Cox proportional hazards and KM analysis in the propensity-adjusted and original populations were used to evaluate metastasis free and overall survival. Results: Median follow-up time was 3.7 years. There were 129 men in the No-RT cohort and 72 in the RT cohort. Those in the No-RT group were twice as likely to develop metastasis (p < 0.05 in all statistical models) and 2-3 times as likely to die of any cause (p 0.03 to 0.12 depending on model) than those receiving RT at any time after surgery. The median time to metastasis in the No RT cohort was 7.3 years and was not-reached in the RT cohort. The median time to death was 11.9 years in the No-RT cohort and was not reached in the RT cohort. Conclusions: The addition of adjuvant or salvage pelvic nodal radiation with limited duration ADT results in clinically and statistically significant reduction in metastasis and death following RP. A nomogram has been created which can be used to predict metastasis and mortality for individual subjects based on pathologic findings after RP.