A. Taniguchi1, Y. Toyomasu2, A. Takada Sr2, T. Mase2, K. Omori2, T. Kawamura2, H. Sakuma2, and Y. Nomoto2; 1Department of Radiology, Mie University Hospital, Tsu, Mie, Japan, 2Department of Radiology, Mie University Hospital, Mie, Japan
Purpose/Objective(s):We prospectively evaluated the treatment outcomes and toxicities of chemoradiotherapy (CRT) with 1.8 Gy per fraction in hypopharyngeal cancer. Materials/
Methods: Between November 2015 and December 2018, the patients received CRT for hypopharyngeal cancer were included. Radiotherapy was delivered at 70.2 Gy in 39 fractions, concurrently with platinum-based chemotherapy. Overall survival (OS), progression-free survival (PFS), and local control (LC) were estimated using the Kaplan-Meier method. Adverse events were assessed using CTCAE version 4.0, and swallowing function was evaluated using the MTF (Method of intake, Time, Food) score at pretreatment, 6 months posttreatment, and 2 years posttreatment. To evaluate adverse events, the relationship between irradiated dose to the pharyngeal constrictor muscles and swallowing function was examined. We contoured the superior constrictor (SC), middle constrictor (MC), inferior constrictor (IC), and whole pharyngeal constrictors (WPC) and analyzed the irradiated dose for each. The Mann-Whitney test was used to analyze correlation between decline in MTF score and mean dose of pharyngeal constrictors. Results: The final cohort of 31 patients (median age, 65 years; 30 males) was enrolled in this study. The primary sites were pyriform sinus (n = 18, 58%), post-cricoid (n = 7, 23%), and posterior pharyngeal wall (n = 6, 19%), respectively. T stages were T1 (n =2, 6%), T2 (n = 12, 39%), T3 (n = 10, 32%), and T4 (n = 6, 19%), respectively. Most patients had Stage ? (n =8, 26%) or Stage? (n = 20, 65%). Mean doses to SC, MC, IC, and WPC were 51.3 Gy (range, 43.0-69.4 Gy), 70.7 Gy (range, 57.4-74.0 Gy), 72.4 Gy (range, 67.1-73.9 Gy), and 60.8 Gy (range, 53.4-71.3 Gy), respectively. The median follow-up time was 61 months. The 5-year OS, PFS, and LC rates were 74%, 68%, and 80%, respectively. Nine patients have died. Six patients experienced local recurrence, 2 patients regional recurrence, and 5 patients distant metastasis. Grade 3 or greater toxicities were observed in 5 patients (16%). One patient (3%) was experienced grade 3 dysphagia. The decline in MTF scores was observed in 12 patients (39%) 6 months after treatment and 5 patients (16%) 2 years after treatment. The patients with the decline in MTF scores received higher dose to SC (p = 0.031), MC (p = 0.039), and WPC (p = 0.011). Conclusion: CRT with 1.8 Gy per fraction for hypopharyngeal cancer showed favorable outcomes.
