Purpose: The present study aimed to investigate the prognostic effect of PD-L1 expressing in tumor and immune cells among patients with esophageal squamous cell carcinoma.
Patients and Methods: We performed a retrospective cohort study by consecutively recruiting 142 patients. The clinicopathological features and PD-L1 expression on tumor and immune cells were independently evaluated by two pathologists.
Results: The median expression rate of PD-L1 was 5% and 30% in tumor and immune cells, respectively. Patients with higher expression of PD-L1 in tumor cells had shorter disease-free and overall survival, and the HRs were 1.52 for relapse (95% CI: 0.88, 2.60) and 1.48 for death (95% CI: 0.82, 2.69). There was no significant association between the PD-L1 expression in immune cells and survival. However, among the patients with PD-L1 expression rate ≤ 30% in immune cells, the high expression rate of PD-L1 in tumor cells was significantly associated with the relapse and death, with HRs of 2.51 (95% CI: 1.25, 5.06) and 3.51 (95% CI: 1.57, 7.85), respectively. Among patients with PD-L1 expression rate > 30% in immune cells, the PD-L1 expression in tumor cells did not show any association with the disease-free and overall survival.
Conclusion: Our study demonstrates that the integration of PD-L1 expression in tumor and immune cells could be used to predict the relapse and survival among patients with esophageal squamous cell carcinoma.
Keywords: esophageal squamous cell carcinoma, PD-L1, prognosis, tumor cells and immune cells, tumor microenvironment