Patients planning to undergo thyroidectomy were recruited between January and December 2010 with the following criteria: (1) age 25-80 years, (2) diagnosed with differentiated thyroid carcinoma, and (3) no previous cancer history. Based on these criteria, 272 patients were eligible for inclusion in the analyses. All participants underwent thyroidectomy as described previously [15 (link)]. The surgical procedures were performed by experienced thyroid surgeons. Prophylactic or therapeutic central neck dissection, which included the pretracheal, prelaryngeal, and paratracheal nodes, was performed on all patients. RAI therapy was recommended 2-4 months after surgery, depending on the risk stratifications included in the guidelines of the American Thyroid Association, after a full interdisciplinary discussion [16 (link)]. All enrolled patients were followed for > 12 months. KT-QoL and Voice Handicap Index 30 (VHI-30) were taken preoperatively and at 1 month, 6 months, and 12 months after surgery. All participants provided a written informed consent according to the policies and procedures approved by the institutional review board of the National Cancer Center, Korea (NCCNCS-09-294).