Abstract:Objective To explore the value of serum microRNA-198 (miRNA-198) and microRNA-182 (miRNA-182) combined with exhaled volatile organic compounds (VOCs) in differentiating space-occupying lesions of the lung.Methods The 150 patients with space-occupying lesions of the lung admitted to the Department of Thoracic Surgery of our hospital from March 2019 to January 2022 were selected and divided into malignant group (n = 85) and benign group (n = 65) according to pathological diagnosis. The general clinical data were compared between the two groups, and serum expressions of miRNA-198 and miRNA-182 were compared between the two groups and among patients with different stages of lung cancer. The values of serum expressions of miRNA-198 and miRNA-182 in predicting the occurrence of lung cancer were analyzed via the receiver operating characteristic (ROC) curves. The detection rates of specific exhaled VOCs were compared between the two groups. The consistency analysis was conducted to compare the efficacy of exhaled VOCs alone and that of serum miRNA-198 and miRNA-182 combined with exhaled VOCs in diagnosing lung cancer.Results There was no statistically significant difference in age, sex composition, body mass index (BMI), history of smoking, history of alcohol consumption, course of disease, family history of tumors, or average diameter of lesions between the two groups of patients (P > 0.05). Compared with the benign group, the serum level of miRNA-198 was lower (P < 0.05) and the serum level of miRNA-182 was higher in the malignant group (P < 0.05). As demonstrated by the ROC curve analysis, the sensitivities of serum expressions of miRNA-198 and miRNA-182 in predicting the occurrence of lung cancer were 0.923 (95% CI: 0.854, 0.973) and 0.953 (95% CI: 0.820, 0.988), with the specificities being 0.812 (95% CI: 0.720, 0.894) and 0.954 (95% CI: 0.910, 0.976). Compared with patients with TNM stage I and Ⅱ lung cancer, the serum expression of miRNA-198 was higher (P < 0.05) and the serum level of miRNA-182 was lower in patients with TNM stage Ⅲ and IV lung cancer (P < 0.05). Compared with patients with TNM stage IV lung cancer, the serum expression of miRNA-198 was higher (P < 0.05) and that of miRNA-182 was lower in patients with stage IV lung cancer (P < 0.05). The detection rates of exhaled cyclopentane, 3-methylpentane and ethylbenzene were different between the malignant group and the benign group (P < 0.05). Specifically, the detection rates of 3-methylpentane and ethylbenzene were higher and the detection rate of cyclopentane was lower in the malignant group than in the benign group (P < 0.05). There was no difference in the detection rates of ethylene, acetone, isoprene, methylcyclopentane, tridecane, toluene, 6-methyl-5-hepten-2-one, N,N-dimethylformamide, nonane, o-xylene, 1,2,4-trimethylbenzene, β-pinene, decane, naphthalene, methyl succinate, and nonanal between the two groups (P > 0.05). With pathological diagnosis set as the gold standard, the sensitivity, specificity, and accuracy of exhaled VOCs in the diagnosis of lung cancer were 0.788 (95% CI: 0.703, 0.814), 0.769 (95% CI: 0.725, 0.844), and 0.780 (95% CI: 0.745, 0.827), and those of serum miRNA-198 and miRNA-182 combined with exhaled VOCs in the diagnosis of lung cancer were 0.965 (95% CI: 0.873, 0.981), 0.846 (95% CI: 0.795, 0.867), and 0.913 (95% CI: 0.826, 0.982), respectively.Conclusions The combination of serum miRNA-198 and miRNA-182 and exhaled VOCs is of certain value in differentiating space-occupying lesions of the lung, and the combined detection exhibits higher sensitivity and accuracy in the diagnosis of lung cancer.