Operative techniques
RFA [11] was used for endoscopic surgery (Coblator II surgery system, EVac70, EIC-7070-01 Radiofrequency Ablation Cutter, Arthrocare Company, U.S.). First, a suspension laryngoscope was inserted, and the lesion was examined under a microscope (LEICA, M520) and using a 0- and 70-degree endoscope. Intraoperative rapid frozen sections were collected during each surgical procedure to identify tumor-free margins. The recent Proposal for Revision of the European Laryngological Society Classification of Endoscopic Cordectomy classified surgical procedures as type I to VI [12]. Among the 65 enrolled patients, there were 31 type III, 17 type IV, 8 type Va, and 9 type VI procedures. External partial surgery was chosen in 28 patients, including 14 Tucker’s reconstructive laryngectomies [13] and 14 larynx-cleaved vocal cord resections.