Association between Swallowing Outcomes and Dose to Critical Swallow Structures in Patients Undergoing Transoral Robotic Surgery and Post-Operative Radiation Therapy

Background The radiation dose to dysphagia and aspiration-related structures (DARS) for patients undergoing transoral robotic surgery (TORS) and post-operative radiation therapy (PORT) for primary oropharyngeal carcinoma is unknown. Methods This prospective study measured swallowing using the MD Anderson Dysphagia Inventory at baseline and then 12-months after PORT. Dosimetric parameters were collected. Results 19 patients were recruited between 2017 and 2019. Worse swallow function at 12-months after PORT was associated with dose-parameters to the oesophageal inlet muscle, superior pharyngeal constrictor muscle and cervical oesophagus. Mean dose, V50Gy, and V60Gy to the base of tongue and pharyngeal constrictors was significantly lower in those receiving PORT to the neck alone. Conclusion Dose to DARS was lower in patients who received PORT to the neck alone. In patients treated with TORS and PORT, poorer swallowing outcomes at 12 months post-treatment were associated with increased dose to oesophageal inlet muscle, superior constrictor muscle, and cervical oesophagus.