Re-irradiation in head and neck cancer: thirteen years of insights.

Background: This study evaluates the long-term outcomes of re-irradiation (Re-RT) using intensity-modulated radiotherapy (IMRT) in patients with locally recurrent or second primary (SP) head and neck cancer (HNC). We aimed to assess locoregional control (LRC), overall survival (OS), and toxicity profiles over a 13-year period, identifying factors influencing treatment outcomes. Materials and methods: We retrospectively analyzed records of 178 patients who underwent Re-RT with IMRT at our institution between January 2010 and October 2023. Re-RT was delivered as adjuvant or definitive treatment. Inclusion criteria included squamous cell carcinoma histology and a performance status of ≥ 2. Patients with unresectable clinical T3/T4 or node-positive disease received concurrent chemotherapy. Primary endpoints were LRC and OS, analyzed using univariate and multivariate Cox regression models. Late toxicity was assessed with a focus on functional outcomes and serious late adverse events. Results: The median follow-up was 39.7 months [95% confidence interval (CI): 32.651-46.277]. The median LRC was 11.23 months (95% CI: 6.845-15.627), with a 3-year LRC rate of 21.9%. The median OS was 26.5 months (95% CI: 21.099-31.411), with a 3-year OS rate of 31.7%. Better LRC was associated with a time interval of > 2 years between RT courses and absence of nodal involvement. Improved OS was associated with adjuvant Re-RT and a time interval of ≥ 2 years. Toxicity analysis revealed manageable late toxicities. Conclusion: Re-irradiation with IMRT is effective for locally recurrent or SP HNC, offering promising survival outcomes with manageable toxicity. Proper patient selection and time intervals between RT courses are critical to optimizing outcomes.