Mucoepidermoid Carcinoma of the Parotid: Very Close Margins and Adjuvant Radiotherapy

Background/Aims: The importance of adjuvant radiotherapy in patients with close margin resections for mucoepidermoid carcinoma of the parotid gland remains unclear. Methods: Patients who underwent parotidectomy for mucoepidermoid carcinoma with or without adjuvant radiotherapy at a single academic tertiary care center from 2000 to 2014 were identified. Included patients had negative but close (<= 2 mm) surgical margins without other high-risk histopathological factors including advanced T-stage, positive nodal disease, lymphovascular or perineural invasion, or high-grade histology. Results: Nineteen patients were identified, of whom 15 (79%) were observed postoperatively, while 4 (21%) underwent adjuvant radiotherapy. There were no significant differences in extent of parotidectomy, elective neck dissection, T staging, or tumor size between patients who were observed and those undergoing adjuvant radiation. There were no locoregional or distant recurrences in any patients at a mean follow up 74.3 months. Patients undergoing adjuvant radiation, however, had significantly more intermediate-grade as compared to low-grade histology (75% vs. 13%, difference 62%, 95% CI 4% to 100%). Conclusions: Patients with negative but close (<= 2 mm) surgical margins without other high-risk histopathological factors have excellent long-term locoregional control with surgery alone. The effects of adjuvant radiotherapy for those who have intermediate-grade disease remain uncertain. (C) 2019 S. Karger AG, Basel