Treatment results of alternating chemoradiotherapy followed by proton beam therapy boost combined with intra-arterial infusion chemotherapy for stage III-IVB tongue cancer.

PURPOSE Proton beam therapy (PBT), compared with conventional radiotherapy, can deliver high-dose radiation to a tumor, while minimizing doses delivered to surrounding normal tissues. The better dose distribution of PBT may contribute to the improvement in local control rate and reduction in late adverse events. We evaluated therapeutic results and toxicities of PBT combined with selective intra-arterial infusion chemotherapy (PBT-IACT) in patients with stage III-IVB squamous cell carcinoma of the tongue. MATERIALS AND METHODS After 2 systemic chemotherapy courses and whole-neck irradiation (36 Gy in 20 fractions), we administered concurrent chemoradiotherapy comprising PBT for the primary tumor [28.6-33 Gy(RBE) in 13-15 fractions] and for the metastatic neck lymph node [33-39.6 Gy(RBE) in 15-18 fractions] with weekly retrograde intra-arterial chemotherapy by continuous infusion of cisplatin with sodium thiosulfate. RESULTS Between February 2009 and September 2012, 33 patients were enrolled. The median follow-up duration was 43 months. The 3-year overall survival, progression-free survival, local control rate, and regional control rate for the neck were 87.0, 74.1, 86.6, and 83.9 %, respectively. Major acute toxicities >grade 3 included mucositis in 26 cases (79 %), neutropenia in 17 cases (51 %), and dermatitis in 11 cases (33 %). Late grade 2 osteoradionecrosis was observed in 1 case (3 %). CONCLUSIONS PBT-IACT for stage III-IVB tongue cancer has an acceptable toxicity profile and showed good treatment results. This protocol should be considered as a treatment option for locally advanced tongue cancer.