Salvage Surgery with Intraoperative Electron Radiation Therapy for Recurrent or Persistent Head and Neck Cancer After Prior Radiotherapy

Background/Objectives: Locoregionally recurrent or persistent head and neck cancer (rpHNC) after prior radiotherapy carries a poor prognosis, and optimal salvage strategies remain uncertain. We evaluated survival, patterns of failure, and 90-day postoperative complications after salvage surgery combined with intraoperative electron radiation therapy (IOERT). Methods: We retrospectively identified 127 previously irradiated patients treated with salvage surgery and IOERT between 1999 and 2023. Overall survival (OS) and disease-free survival (DFS) were estimated using the Kaplan–Meier method, and locoregional failure (LRF) and distant failure were estimated using Aalen–Johansen cumulative incidence with death as a competing event. Associations were evaluated one predictor at a time in age- and sex-adjusted Cox (OS, DFS) and Fine-Gray (LRF) models without multiplicity adjustment, and they are exploratory. Results: With a median follow-up of 70 months, median overall survival (OS) was 20.5 months (95% CI, 14.6–40.2), with 1-, 2-, and 3-year OS rates of 63%, 48%, and 43%, respectively. Median disease-free survival (DFS) was 8.8 months. Positive surgical margins and extranodal extension (ENE) were associated with worse OS in separate age- and sex-adjusted models. The 1-, 2-, and 3-year cumulative incidences of LRF were 34.3%, 44.7%, and 49.8%, respectively. The corresponding cumulative incidences of distant failure were 21.6%, 24.0%, and 26.7%, respectively. Thirty-seven patients had a documented distant failure, of whom 27 (73%) experienced distant failure within one year. Available records documented three deaths within 90 days (3/127, 2.4%). Conclusions: Among rpHNC patients treated with this IOERT-containing multimodality salvage strategy, median OS was 20.5 months. Because the study lacked a salvage-surgery-only comparator, postoperative treatments were selectively administered, and complication reporting was incomplete, neither the efficacy nor the comparative safety of IOERT can be determined from these data.