How often parapharyngeal space is encountered in TORS oropharynx cancer resection

Early stage oropharyngeal squamous cell carcinoma (OPSCC) may occasionally invade parapharyngeal space (PPS). Tumor invasion of PPS structures such as the carotid artery, internal jugular vein and cranial nerves IX-XII may add significant morbidity. We analyzed 73 patients who underwent transoral robotic surgery (TORS) for OPSCC between 2008 and 2012. Patients were selected based on preoperative evaluation including detailed physical and endoscopic examination, neck CT and/or PET-CT scan. T1, T2 and selected T3 cases were included in this study. None of the patients had obvious PPS extension on preoperative evaluation. All patients had OPSCC in palatine tonsil (60; 82.2 %) and base of tongue (13; 17.8 %). Twenty-seven patients had cT1 (37 %), 39 had cT2 (53.4 %), and 7 had cT3 (9.6 %) disease in clinical and radiologic evaluation. None of the oropharyngeal lesions had obvious radiologic PPS extension prior to operation. During TORS procedure, we encountered PPS in 18 (24.6 %) patients while resecting the deep margin. These parapharynx resections involved external carotid artery in 1, medial pterygoid muscle in 2, and parapharyngeal fat with or without styloid musculature in the remaining 15 patients. Except three cases, we were able to remove the lesions en bloc with negative surgical margins. TORS resection of oropharyngeal cancer extending to PPS appears to be a safe and feasible technique with minimal complications. Significant experience with TORS and further understanding of the endoscopic anatomy of PPS could obviate the morbidity associated with tumor resection in this dense neurovascular region.