This is a single-center, open-label, randomized, controlled, exploratory clinical trial designed to evaluate the efficacy and safety of de-escalated surgery compared with standard surgery in patients with resectable locally advanced head and neck squamous cell carcinoma (LA-HNSCC) who achieved a partial response (PR) or complete response (CR) after neoadjuvant immunochemotherapy. Eligible patients will be randomly assigned in a 1:1 ratio to either the de-escalated surgery group (experimental) or the standard surgery group (control). The de-escalated surgery group will undergo limited tumor resection and selective neck dissection based on clinical and imaging response, while preserving important anatomical structures and functions when feasible. The control group will receive standard surgical treatment following NCCN guidelines. All patients will be evaluated using RECIST 1.1 criteria for radiological response and will undergo enhanced CT or MRI at baseline, before the second cycle of neoadjuvant therapy, within one week before surgery, 30 days after surgery, and every 3 months thereafter until 2 years post-surgery, disease recurrence, death, or study completion. The study aims to assess whether de-escalated surgery can achieve similar oncologic outcomes while improving postoperative function and quality of life. The primary endpoints are disease-free survival (DFS), health-related quality of life (HRQoL), and 3- and 5-year overall survival rates (OS rate). A total of 60 patients will be enrolled over a 3-year period, with 30 in each group.