Hypofractionated Spot Scanning Proton Therapy for Head and Neck Mucosal Melanoma: A Retrospective Analysis With Quality-of-Life Outcome.

Abstract

To evaluate clinical outcomes and quality of life (QOL) following hypofractionated spot-scanning proton therapy (SSPT) for head and neck malignant mucosal melanoma (HNMM). This retrospective study included 39 patients treated with SSPT (60-64 Gy[RBE] in 15-16 fractions) between 2013 and 2023. Endpoints included overall survival (OS), local control (LC), progression-free survival (PFS), toxicities, and QOL. Most tumors were located in the sinonasal cavity (n = 32). Surgery was performed in 8 patients; 19 received immune checkpoint inhibitors post-SSPT. The 3-year OS, LC, and PFS were 50%, 83%, and 30%, respectively. Larger tumor volumes (≥ 20 cm³) were linked to worse PFS. Grade 3 mucositis occurred in 13%. Late toxicities included sinus disorder, osteonecrosis, and blindness (3%-5%). QOL was largely preserved, with notable declines in pain, swallowing, and mouth opening. SSPT provides favorable LC with acceptable toxicity. Effective systemic therapies are needed to improve long-term outcomes.