Abstract: Objective To systematically analyze the expression characteristics of peripheral blood lymphocyte subsets in patients with newly diagnosed lung cancer at different disease stages, and to explore their correlations with clinicopathological features, gender, age and other factors. Methods A total of 183 patients with newly diagnosed untreated lung cancer (106 early-stage, 77 late-stage) from January 2019 to December 2020 were enrolled. Flow cytometry was used to detect 28 peripheral blood lymphocyte subsets and activation markers. Comparisons between groups were performed using t-test, Welch t-test, or Mann-Whitney U test, and subgroup analyses were conducted based on age, gender, pathological type, and metastatic site. Results Early-stage patients exhibited higher levels of lymphocytes, B cells, CD4⁺ T cells, and CD28 (P＜0.05), while late-stage patients showed significant increase in white blood cell count, NK cell proportion, and CD8⁺ T cell activation markers (P＜0.001). Subgroup analyses revealed that in the early-stage elderly group, NK cell proportion was higher than that in the younger group (P＜0.001), while B cell proportion was lower (P＜0.05); in early-stage lung squamous cell carcinoma, white blood cell count was higher than that in adenocarcinoma (P＜0.05), while adenocarcinoma exhibited higher lymphocyte and B cell proportions (P＜0.05); in late-stage squamous cell carcinoma, lymphocyte, NK cell, and CD8⁺CD38⁺ activation levels were lower than those in adenocarcinoma (P＜0.05); patients with pulmonary metastasis showed lower expression of CD8⁺HLA-DR⁺ and CD8⁺CD38⁺ compared with those without pulmonary metastasis (P＜0.05); patients with multiple metastases showed lower expression of CD4⁺CD28⁺ percentage and CD8⁺CD28⁺ compared with those with solitary metastasis (P＜0.05). Conclusions There are systematic differences in peripheral immune characteristics between patients with early-and late-stage lung cancer, which are influenced by various clinical factors including age, gender, pathological type, and metastatic site, providing a basis for disease staging assessment and individualized treatment strategies based on peripheral immune phenotypes.

Key words: non-small cell lung cancer, lymphocyte subsets, lung squamous cell carcinoma, lung adenocarcinoma