In resectable locally advanced oral cavity cancer and oropharyngeal cancer, SBRT with the total dose of 18 Gy by three fractions will be delivered to the primary tumor and metastatic lymph nodes every other day. One week later, neoadjuvant chemoimmunotherapy of Sindilizumab (200mg) plus docetaxel (75mg/m2) and cisplatin (75mg/m2) will be administered every three weeks for three cycles. Then radical surgical resection will be performed and postoperative radiotherapy with or without chemotherapy will be supplemented according to the initial tumor staging and postoperative pathologic characteristics. The investigators aim to evaluate the pathological complete response rate and safety of the combined treatment of SBRT with chemoimmunotherapy in locally advanced cancers of oral cavity and oropharynx.

Inclusion Criteria:

• pathologically confirmed squamous carcinoma of oral cavity or oropharynx
• III-IVa based on the eighth edition of AJCC
• aged 18 to 70
• ECOG PS 0-1
• no organ dysfunction
• Expected survival ≥ 3 months

Exclusion Criteria:

• diagnosed with other malignant tumors
• has autoimmune diseases or serious mental illness
• at high risk of hemorrhage
• Systemic or local glucocorticoid therapy within 4 weeks
• Comorbidities requiring long-term treatment with immunosuppressive drugs or systemic or topical corticosteroids in immunosuppressive doses
• Patients with active tuberculosis (TB) who are receiving anti-tuberculosis treatment or have received anti-tuberculosis treatment within 1 year prior to screening.
• Prior use of anti-PD-1 antibody, anti-PD-L1 antibody, anti-PD-L2 antibody, or anti-CTLA-4 antibody
• HIV or HCV
• HBsAg positive with positive HBV DNA copy number (quantitative test) ≥1000cps/ml