CD8A and esophageal squamous cell carcinoma: Finally, multivariate Cox regression analysis showed gender (HR, 0.214; 95% CI, 0.058–0.794; p = 0.021), CD39-expressing CD8+ T cells in the CK+ region (HR, 2.587; 95% CI, 1.077–6.213; p = 0.033), and CD39-expressing CD8+ T cells in the CK− region (HR, 3.090; 95% CI, 1.352–7.064; p = 0.008) as independent prognostic factors for ESCC (Table 2) (Figure 3a).