Comparative Analysis of 5-Year Clinical Outcomes and Patterns of Failure of Proton Beam Therapy Versus Intensity Modulated Radiation therapy for Prostate Cancer in the Postoperative Setting

Purpose Although proton beam therapy (PBT) is a rapidly expanding modality to treat prostate cancer compared with intensity modulated radiation (IMRT), data comparing disease control outcomes and patterns of failure in the postprostatectomy setting remain substantially limited. Methods Materials All patients who underwent postoperative IMRT or PBT bed only at single institution were included (2009-2017). Endpoints biochemical (BF; using institutional recent cooperative group trial definitions), local (LF), regional (RF), distant (DF), all-cause mortality. A case-matched cohort analysis was performed 3-to-1 nearest-neighbor matching; multivariable Cox proportional hazards modeling (MVA) estimated hazard ratios for disease-related by treatment modality. Results Of 295 men, 260 matched (n = 65 PBT, 195 IMRT); after matching, age diagnosis (P < .01) significantly differed between cohorts. At median follow-up 59 months, BF (institution-defined), LF, RF, DF, mortality rates 45% 29), 2% 1), 9% 6), 1) 41% 80), 3% 5), 7% 13), 18), 5% 9) (all P > .05). RT not associated on MVA definitions .05), nor LF .82), RF .11), DF .36), .69). Patterns qualitatively similar cohorts (DF: bone, retroperitoneal nodes, lung). Conclusions In this institution, analysis, yielded long-term setting.