A retrospective study by Southern Tohoku Proton Therapy Center, Japan, analyzed 30 patients with T4 squamous cell carcinoma of the maxillary gingiva treated with radiation and intra-arterial infusion chemotherapy. Radiotherapy was 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 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. The authors suggested that PBT in combination with intra-arterial infusion chemotherapy was not inferior to other treatment protocols and should be considered as a safe and effective option.