Efficacy and Safety of a Third-Course of Neoadjuvant Immunochemotherapy Combined With SBRT in Locally Advanced Head and Neck Squamous Cell Carcinoma Patients With Stable Disease After Two Treatment Courses: A Single-Arm Exploratory Study

Patient will receive SBRT (8Gy\*3F) in combination with the original regimen of neoadjuvant immunochemotherapy in course 3. Gross tumor target volume (GTV) based on the primary foci clearly identified by clinical and imaging examinations. The GTV was discharged 3 mm to generate a Planning target volume (PTV). the target area (PTV) was dosed accordingly to the PTV.