Zhongguo quanke yixue (Jun 2022)
Expression of Programmed Death Ligand 1 and Density of CD8+ Tumor-infiltrating T-lymphocytes in Gastric Cancer Tissues and Their Relationship with Clinicopathological Characteristics and Prognosis of Patients with Gastric Cancer
Abstract
Background At present, whether the expression of programmed death ligand 1 (PD-L1) and the density of CD8+ tumor-infiltrating T lymphocytes (TILs) in gastric cancer tissue can be used as prognostic indicators for gastric cancer patients has been still unclear. Objective To analyze the expression of PD-L1 and density of CD8+ TILs in gastric cancer tissues and their relations with clinicopathological characteristics and prognosis of patients with gastric cancer. Methods A total of 125 gastric cancer patients underwent surgical treatment in Nanyang First People's Hospital from January 2016 to March 2018 were selected, and the expression level of PD-L1 mRNA in gastric cancer tissue was detected by real-time fluorescence quantitative polymerase chain reaction, the density of CD8+ TILs in gastric cancer tissue was detected by immunohistochemical methods. The relations of the relative expression quantity of PD-L1 mRNA and the density of CD8+ TILs in gastric cancer tissue with the clinicopathological characteristics of patients with gastric cancer was analyzed; the correlation between the relative expression quantity of PD-L1 mRNA and the density of CD8+ TILs in gastric cancer tissue was analyzed by Pearson correlation analysis; telephone follow-up was conduct till to 36 months after operation, taking death or loss to follow-up as outcome event, Kaplan-Meier survivorship curve was drawn to conduct survival analysis; univariate and multivariate Cox regression analysis was used to analyze the influencing factors of prognosis of gastric cancer patients. Results The average relative expression quantity of PD-L1 mRNA was 3.1 in gastric cancer tissue, the average number of CD8+ TILs was 36 in cancer nests, thus the 125 patients were divided into low-level group (with relative expression quantity of PD-L1 mRNA less than 3.1, n=73) , high-level group (with relative expression quantity of PD-L1 mRNA equal or over 3.1, n=52) , low-density group (with number of CD8+ TILs less than 31, n=55) and high-density group (with number of CD8+ TILs equal or over 31, n=70) . There were significant differences in lymph node metastasis, vascular invasion and peritoneal metastasis between the the low-level group and high-level group (P<0.05) , so as in depth of infiltration, incidence of lymphatic metastasis, vascular invasion and peritoneal metastasis between the the low-density group and high-density group (P<0.05) . Pearson correlation analysis showed that the relative expression quantity of PD-L1 mRNA was negatively correlated with density of CD8+ TILs in gastric cancer tissue (r=-0.412, P<0.001) . We found 88 cases with good prognosis and 37 cases with poor prognosis, with the medium time of follow-up of 36 months; there was significant difference in Kaplan-Meier curve between low-level and high-level groups, low-density and high-density groups, respectively (P<0.05) . Multivariate Cox regression analysis showed that high-level PD-L1 mRNA〔HR=3.021, 95%CI (1.632, 5.045) 〕and low-density CD8+ TILs〔HR=2.158, 95%CI (1.854, 4.632) 〕were independent risk factors of poor prognosis of patients with gastric cancer (P<0.05) . Conclusion High level of PD-L1 mRNA and low density of CD8+ TILs are independent risk factors of poor prognosis in gastric cancer patients, which are expected to be biomarkers for poor prognosis in gastric cancer patients.
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