Skull Base--Cancer

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.

The Quality of Life of patients treated with hadrontherapy is still limited. Two cohorts are established, they will be receiving specific standardized questionnaires to be evalutaed in their results.