Bates JE, et al. - The efficacy of adjuvant radiotherapy (RT) in high-grade retroperitoneal sarcoma (RPS) given the known benefits of RT for local control and overall survival (OS) in patients with high-grade extremity soft tissue sarcoma was determined. Improved OS was reported in high-grade RPS patients who received post-operative RT. Adjuvant RT should be considered for all patients with high-grade RPS.