Abstract： Objective To investigate the clinical value of peripheral blood neutrophil extracellular traps(NETs)markers in patients with pulmonary infections after radical gastrectomy for gastric cancer.Methods A total of 403 gastric cancer patients who underwent radical gastrectomy at the 922nd Hospital of the Joint Service Support Force of the PLA from May 2015 to August 2022 were selected for the study.Patients were divided into three groups based on postoperative pul-monary infection status:non-infection group(n=332),non-pulmonary infection group(n=43),and pulmonary in-fection group(n=28).Preoperative and postoperative serum inflammatory markers,including white blood cells(WBC),neutrophil-to-lymphocyte ratio(NLR),high-sensitivity C-reactive protein(hs-CRP),vascular endothelial growth factor(VEGF),tumor necrosis factor-alpha(TNF-α),interleukin(IL)-1 β,IL-6,IL-8,and NETs-related markers cell-free DNA(cf-DNA),myeloperoxidase-DNA(MPO-DNA)complexes,and citrullinated histone H3(CitH3),were compared among the three groups.The correlation between peripheral blood NETs markers and serum in-flammatory markers was analyzed using Pearson correlation analysis.Receiver operating characteristic(ROC)curve analy-sis was employed to assess the diagnostic value of peripheral blood NETs markers for postoperative pulmonary infection in gastric cancer patients.Results Postoperatively,compared with the non-infection group,the non-pulmonary infection and pulmonary infection groups showed significant increases in serum inflammatory markers,including WBC,NLR,hs-CRP,VEGF,TNF-α,IL-1β,IL-6,and IL-8(all P＜0.05).The non-pulmonary infection group exhibited sig-nificantly elevated peripheral blood cf-DNA levels,while the pulmonary infection group had significantly higher levels of cf-DNA,MPO-DNA complexes,and CitH3(all P＜0.05).Compared with the non-pulmonary infection group,the pulmonary infection group showed significant increases in NLR,hs-CRP,TNF-α,IL-6,and IL-8 levels,and Ci-tH3 expression(all P＜0.05).Pearson correlation analysis revealed a positive correlation between peripheral blood NETs markers(cf-DNA,MPO-DNA complexes,and CitH3)and serum TNF-α(r=0.275,0.204,0.238,P＜0.05).ROC curve analysis demonstrated that the areas under the curve(AUCs)for cf-DNA,MPO-DNA,and CitH3 in diag-nosing postoperative pulmonary infection in gastric cancer patients were 0.809,0.700,and 0.751,respectively.Conclu-sion Peripheral blood NETs markers cf-DNA,MPO-DNA complexes,and CitH3 are positively correlated with postop-erative pulmonary infections in gastric cancer and have significant diagnostic value for postoperative pulmonary infections.