CD8A and esophageal squamous cell carcinoma: Previous studies have shown that the proportion of PD-L1–expressing immune cells and high CD8+ tumor cell densities significantly increased in patients with ESCC after NCT.69 In addition, cell experiments found that the expression of PD-L1 on the ESCC cell surface was significantly increased in a dose-dependent manner after 24 hours of radiation exposure.70 These findings suggest that chemotherapy and radiotherapy may achieve sensitization to immunotherapy by inducing increased expression of PD-L1 on cells.