Postoperative Radiotherapy for Oral Cavity Squamous Cell Carcinoma: Real-world Outcomes and the Impact of Time to Radiotherapy Initiation

A BSTRACT Objectives: To assess the real-world outcomes of postoperative radiotherapy (PORT) for oral cavity squamous cell carcinoma and to examine whether delay in starting PORT affects the survival. Methods: We retrospectively reviewed 47 consecutive patients who underwent curative surgery followed by PORT. Radiotherapy was delivered using standard planning procedures, with 66 Gy in 33 fractions for high-risk patients and 60 Gy in 30 fractions for low-risk patients. Time from surgery to PORT initiation was evaluated both continuously and as ≤6 weeks versus >6 weeks. Overall survival (OS) and progression-free survival (PFS) were measured from the start of radiotherapy and analyzed using the Kaplan–Meier methods and multivariable Cox regression. Results: The median interval from surgery to PORT was 6.1 weeks (range, 2.7–9.1). With a median follow-up of 19.4 months, the 2-year OS and PFS rates were 62.3% and 39.1%, respectively. Two-year OS was 77.8% in the ≤6-week group versus 49.0% in the >6-week group ( P = 0.045). Two-year PFS was 52.2% versus 26.1%, respectively ( P = 0.062). In multivariable analysis, PORT initiation >6 weeks after surgery was independently associated with worse PFS (hazard ratio 2.865, 95% confidence interval: 1.065–7.709; P = 0.037). Conclusion: In this real-world cohort, delayed initiation of PORT beyond 6 weeks after surgery was associated with inferior outcomes, including significantly worse PFS. Optimizing postoperative treatment timelines may improve the outcomes in oral cavity squamous cell carcinoma.