Postoperative Radiotherapy With Nimotuzumab ± Benmelstobart in Intermediate-Risk Head and Neck Squamous Cell Carcinoma

Inclusion Criteria: * Age ≥ 18 years * ECOG performance status: 0-2 * Histologically confirmed squamous cell carcinoma of the head and neck (oral cavity, oropharynx, larynx); oropharyngeal cancer must be p16-negative (p16 positivity defined as ≥70% staining) * Completionof curative-intent surgery, with any of the following intermediate-risk factors present postoperatively: ①pT3-4a; ②N2 disease (excluding cases with extranodal extension); ③Closemargin \< 5 mm; ④Lymphovascular and/or perineural invasion; ⑤Invasion depth \> 5mm for T2 oral cavity cancer * Laboratory tests must meet the following criteria: ①Hematologic parameters (within 14 days without transfusion or blood products): a. Hemoglobin (Hb) ≥80 g/L; b.Absolute neutrophil count (ANC) ≥ 1.0 × 10⁹/L; c. Platelet count (PLT) ≥ 80 × 10⁹/L; ②Biochemical parameters: a. Bilirubin (BIL) \< 1.5 × upperlimit of normal (ULN); b.Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 × ULN; * Expected survival time ≥ 6 months; * Women of child bearing potential must have a negative pregnancy test (serum or urine) within 7 days prior to enrollment and agree to use reliable contraception during the study period; Male subjects must use reliable contraception from before treatment initiation until 120 days after the last dose of study drug * With PD-L1 immunohistochemistry testing * Participant voluntarily agrees to participate in this study and signs the informed consent form Exclusion Criter…