CD8A and esophageal squamous cell carcinoma: Similarly, in our study, the univariate and multivariate analyses of circulating lymphocyte subsets in patients with ESCC showed that the post-RT percentage of CD8+ T cell was negatively correlated with the occurrence of RP, while pre- and post-RT percentage of CD8+ T cell were negative risk factors of ≥ grade 2 RP toxicity.