Carbon Ion Re-Irradiation for Recurrent Head-and-Neck Cancer: A Single-Institutional Experience

Abstract Background This study aimed to assess the feasibility of carbon ion re-irradiation (CIR) for recurrent head and neck cancer (HNC). Methods This retrospective study included 229 patients with recurrent HNC that were treated with CIR between 2010 and 2017. We assessed progression-free survival (PFS), overall survival (OS), pattern of failure, and toxicity. Of the primary tumors, 54.1% were adenoid cystic carcinomas, 26.2% were squamous cell carcinomas, 8.3% were adenocarcinomas, and 11.4% were other tumor entities. Results The median radiotherapy interval was 3.9 years (range, 0.3–46.5 years), and patients received a median dose of 51 Gy (relative biological effectiveness [RBE]; range, 30–66 Gy [RBE]) in 3 Gy (RBE) fractions. The median cumulative lifetime dose after CIR was 132.8 Gy (range, 88.8–155.0 Gy). The median local PFS after CIR was 24.2 months (95% confidence interval [CI] 19.4–29.0 months), and the median OS was 26.1 months (95% CI 21.9–30.3 months). Serious acute toxicity (≥ grade III) after CIR included laryngeal edema, grade IV (n = 2; 0.9%); dysphagia, grade III (n = 3; 1.3%); fistula, grade III (n = 1; 0.4%); and impaired hearing, grade III (n = 1; 0.4%). Late toxicities of grades III or higher (n = 18; 14.5%) included central nervous system necrosis, grades IV/III (n = 1; 0.8%/n = 5; 4.0%); optic nerve disorder, grades IV/III (n = 2; 1.6%/n = 2; 1.6%); impaired hearing, grade III (n = 5; 4.0%), osteonecrosis, grade III (n = 1; 0.8%); and carotid blowout, grade IV (n = 1; 0.8%). Conclusion In patients with locally recurrent HNC, CIR was a feasible, effective treatment with acceptable toxicity and good local control. Thus, CIR represented a valuable alternative to surgical salvage and palliative chemotherapy in selected patients.