Adjuvant Proton Beam Radiation Therapy for Sinonasal Mucosal Melanoma

Background: Head and neck mucosal melanoma (HNMM) is rare and carries a poor prognosis with high rates of disease progression. There is little data regarding the use of adjuvant proton radiation therapy in the management of sinonasal HNMM. Aims: We performed a retrospective review of patients with nonmetastatic sinonasal HNMM treated with adjuvant proton radiation from 2012 to 2022 at a single academic institution. Kaplan–Meier estimates were used for survival analyses. Methods and Results: Eight patients with sinonasal HNMM were treated with surgery and adjuvant proton radiation, and six received systemic therapy. Median follow-up was 15 months (range: 3–68 months). Only one local failure was observed, and two patients developed distant metastases. Kaplan–Meier 1-year results were as follows: local control 88%, distant metastasis-free survival 75%, and overall survival 88%. No Grade 3 or higher late toxicities were observed. Conclusion: Surgical resection and adjuvant proton radiation provided early favorable local control and toxicity profiles in our cohort of patients with sinonasal HNMM. Further multi-institutional work is needed to study this rare malignancy.