Expression and Prognostic Value of PD-1 of Tumor or Immune Cancer Cells in Early-Stage Lung Adenocarcinoma

Objective The molecular mechanism of programmed cell death-ligand 1 （PD-L1） in tumor cells and its clinical value had been widely explored. However, the research of programmed cell death-1 （PD-1） on tumor cells and immune cells was still lacking. Our article aimed to explore the PD-1 expression on immune cells and tumor cells respectively. Otherwise, we also explored the correlation of PD-1 and clinicopathological features, and its recurrence risk in patients with early-stage lung adenocarcinoma. Methods In this study, patients with early-stage lung adenocarcinoma were enrolled from Guangdong Provincial People's Hospital between April 2010 and June 2021. PD-1 protein expression was assessed by immunohistochemical （IHC） on tumor cells and immune cells, respectively. Results 446 early-stage lung adenocarcinoma patients meeting the criteria were analyzed. The positive expression rate of PD-1 on tumor cells was 2.2% （10/446）, and the positive expression rate of PD-1 on immune cells was 18.2% （81/446）. Binary logistics regression analysis showed that positive PD-1 expression on immune cells was more likely to happen in smoking patients （vs. non-smoker） odds ratio （OR） 2.059, 95% confidence interval （CI） 1.138~3.723, P<0.05, PD-1 positive expression on tumor cells are more likely to happen in stage Ⅲ patients （vs. stageⅠ） （OR: 45.92, 95%CI 5.616~375.507, P<0.05）, and there was a positive correlation between PD-1 expression on tumor cells and PD-1 expression on immune cells （r=0.58,P<0.05）. Kaplan-Meier survival analysis showed that the patients of tumor cell PD-1 positive expression had a higher risk of recurrence hazard ratio （HR） 6.5, 95%CI 1.227~34.590, disease-free survival （DFS）: P<0.05, and PD-1 expression on immune cells was not related to the risk of recurrence （DFS: P=0.26）. Conclusions The positive expression of PD-1 on tumor cells may be a poor prognostic factor after surgery in patients with early-stage lung adenocarcinoma.