High-dose stereotactic radiotherapy boost in the radical treatment of head and neck tumors

The current results of head and neck cancer treatment remain suboptimal therefore, novel approaches are needed to improve its effectiveness. This prospective, single-center study aims to assess the results and safety of combining conventionally fractionated radiotherapy with a high-dose stereotactic radiotherapy boost in radical treatment. Twenty-eight patients with head and neck tumors of diverse localizations and histopathologies were recruited. The stereotactic boost was delivered to primary tumors or metastatic nodes up to 6 days before or after conventional radiotherapy. The boost doses ranged from 8 to 18 Gy. A complete response was observed in 25 patients (89%). The response did not depend on boost size or its timing within the regimen. Disease progression caused death in 5 cases. Positive surgical margins increased the risk of metastasis eighteenfold (p = 0.015) and mortality threefold (p = 0.030). A higher Zubrod performance status correlated with greater acute mucosal and skin toxicity. The most severe late complications were carotid blow-out syndrome (with actinomycosis coinfection) and brain necrosis. The risk of late toxicity increased after exceeding a biological effective dose of 143.33 Gy (p = 0.0148). A boost with a dose of 10 Gy represents a promising treatment option with permissible tolerance, with higher doses offering similar efficacy but greater late toxicity. The study protocol was approved by the local Bioethics Committee (KB/430 − 87/19) and registered on the ClinicalTrials.gov (NCT06472570) on 25 June 2024.