Proton Beam Therapy in Combination with Intra-Arterial Infusion Chemotherapy for T4 Squamous Cell Carcinoma of the Maxillary Gingiva

This study aimed to evaluate the therapeutic effect and toxicity of proton beam therapy in combination with intra-arterial infusion chemotherapy in patients with squamous cell carcinoma of the maxillary gingiva. Between December 2010 and March 2016, 30 patients with T4 squamous cell carcinoma of the maxillary gingiva were treated with radiotherapy and retrograde intra-arterial infusion chemotherapy using cisplatin (20⁻40 mg/m², 4⁻6 times). Radiotherapy was basically administered using boost proton beam therapy for primary tumor and neck lymph node tumors, following 36⁻40 Gy photon radiation therapy delivered to the prophylactic area, to a total dose of 70.4⁻74.8 Gy. The median follow-up was 33 months. The 3-year local control and overall survival rates were 69% and 59%, respectively. Major grade 3 or higher acute toxicities included mucositis, neutropenia, and dermatitis in 12 (40%), 5 (17%), and 3 (10%) patients, respectively. No grade 3 or higher late toxicities were observed. These results suggested that proton beam therapy in combination with intra-arterial infusion chemotherapy was not inferior to other treatment protocols and should be considered as a safe and effective option in patients with T4 squamous cell carcinoma of the maxillary gingiva.