Carbon Ion Reirradiation for Recurrent Head and Neck Cancer: A Single-Institutional Experience.

PURPOSE: This study aimed to assess the feasibility of carbon ion reirradiation (CIR) for recurrent head and neck cancer (HNC).

METHODS AND MATERIALS: This retrospective study included 229 patients with recurrent HNC who were treated with CIR between 2010 and 2017. We assessed progression-free survival, overall survival, 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 radiation therapy 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 progression-free survival after CIR was 24.2 months (95% confidence interval, 19.4-29.0 months), and the median overall survival was 26.1 months (95% confidence interval, 21.9-30.3 months). Serious acute toxicity (grade ≥3) after CIR included laryngeal edema, grade 4 (n = 2; 0.9%); dysphagia, grade 3 (n = 3; 1.3%); fistula, grade 3 (n = 1; 0.4%); and impaired hearing, grade 3 (n = 1; 0.4%). Late toxicities of grades 3 or higher (n = 18; 14.5%) included central nervous system necrosis, grades 4/3 (n = 1; 0.8%/n = 5; 4.0%); optic nerve disorder, grades 4/3 (n = 2; 1.6%/n = 2; 1.6%); impaired hearing, grade 3 (n = 5; 4.0%), osteonecrosis, grade 3 (n = 1; 0.8%); and carotid blowout, grade 4 (n = 1; 0.8%).

CONCLUSIONS

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.