Results Of Postoperative Interstitial Brachytherapy Of Resectable Floor Of Mouth Tumors

PURPOSE: The purpose of this study was to describe the results of postoperative sole interstitial brachytherapy (BT) in patients with resectable floor of mouth tumors.METHODS AND MATERIALS: Between January 1998 and December 2017, 44 patients with squamous cell histology, stage T1-3N0-1M0 floor of mouth tumor were treated by excision of the primary lesion with or without neck dissection followed by sole high-dose-rate tumor bed BT with an average dose of 22.7 Gy (10-45 Gy) using rigid metal needles (n = 14; 32%) or flexible plastic catheters (n = 30; 68%).RESULTS: During a median followup time of 122 months for surviving patients, the probability of 5-and 10-year local and regional tumor control, overall survival (OS), and disease-specific survival (DSS) was 89% and 89%, 73% and 67%, 52% and 32%, 66% and 54%, respectively. In univariate analysis, lymphovascular invasion was a negative predictor of regional tumor control (p = 0.0062), DSS (p = 0.0056), and OS (p = 0.0325), whereas cervical recurrence was associated with worse DSS (p < 0.0001) and OS (p < 0.0001). The incidence of local Grade 1, 2, and 3 mucositis was 25%, 64%, and 11%, respectively. Grade 4 side effect, that is soft tissue necrosis occurred in four cases (9%).CONCLUSIONS: Results of postoperative sole high-dose-rate BT of floor of mouth tumors are comparable with those reported with low-dose-rate BT, and this method could improve local tumor control and DSS compared with exclusive surgical treatment. (C) 2020 Published by Elsevier Inc. on behalf of American Brachytherapy Society.