 It is a single-arm phase II trial. The target population is patients with histologically diagnosed locally advanced ESCC patients clinically staged at least T3 andor any N and M0 by endoscopic ultrasonography EUS and fludeoxyglucose-positron emission tomography FDG-PET who have received preoperative cisplatin-based chemoradiotherapy CRT followed by surgery, and exhibit high risk closed or involved resection margin or extranodal invasion of involved lymph nodes of tumor recurrence. Eligible patients will receive adjuvant cisplatin-based CRT followed by pembrolizumab for 18 cycles.The study will enroll 46 patients in Taiwan. The estimated enrollment period is 2 years. 