CD274 and esophageal squamous cell carcinoma: Wang et al. retrospectively analyzed 146 patients with esophageal squamous cell carcinoma (ESCC) to investigate the relationship between the expression of PD-L1 and infiltration of CD8+ T cells in tumor immune microenvironment with the prognosis of ESCC patients, and it was found that PD-L1 expression was significantly associated with poor overall survival; however, CD8+ T cell infiltration is not a risk factor for prognosis [33].