pembrolizumab+cisplatin + 5-FU
Combination Productivgtt, pembrolizumab 200mg d1+cisplatin20 mg/m2 qd d1-d3 + 5-fluorouracil 3000mg/m2 last for 120hours, six circles. Subjects will undergo surgery after receiving neoadjuvant chemotherapy within 3 weeks, followed by adjuvant therapy and pembrolizumab alone maintenance treatment.