This prospective, single-arm, Phase II clinical trial aims to evaluate the efficacy and safety of tislelizumab combined with chemotherapy as neoadjuvant therapy and postoperative adjuvant immunotherapy in patients with skull base-invading head and neck squamous cell carcinoma. The primary objectives are to address the following questions:
* What are the objective response rate and pathological response of tislelizumab combined with chemotherapy as neoadjuvant therapy in patients with skull base-invading head and neck squamous cell carcinoma?
* Can neoadjuvant therapy convert unresectable skull base-invading head and neck squamous cell carcinoma into a resectable condition?
* Can adjuvant immunotherapy after neoadjuvant therapy prolong patients' recurrence-free survival and overall survival? The researchers will administer neoadjuvant therapy (tislelizumab combined with chemotherapy) and adjuvant immunotherapy to patients with skull base-invading head and neck squamous cell carcinoma and assess the treatment's efficacy and safety.
Participants will:
* Receive neoadjuvant therapy every 3 weeks (tislelizumab 200mg on Day 1, nab-paclitaxel 260mg/m² on Day 1, cisplatin 75mg/m² on Days 1-3) for 3 cycles.
* Undergo surgical treatment within 3 weeks after completing neoadjuvant therapy.
* Receive (chemo)radiotherapy 4-6 weeks after surgery.
* Receive adjuvant immunotherapy (tislelizumab 200mg) every 3 weeks after (chemo)radiotherapy for 8 cycles.