Objective To investigate the predictive effect of serum interleukin-38（IL-38） on the occurrence of pulmonary embolism in primary lung cancer.Methods Using a random sampling method

42 patients with primary lung cancer combined with pulmonary embolism who were hospitalized in a hospital in Kaifeng from January 2017 to December 2019 were selected as the pulmonary embolism group

and 126 patients with primary lung cancer not combined with pulmonary embolism who were treated in this hospital during the same period were randomly selected as the control group with a 3-fold observation sample size.The differences in clinical indicators between the 2 groups were compared

and the risk factors for the development of pulmonary embolism in primary lung cancer were analyzed by multi-factor logistic regression

and the predictive effect of IL-38 on the development of pulmonary embolism in primary lung cancer was examined using the receiver operating characteristic（ROC） curve.Results The differences in age

oxygenation index

pulmonary artery systolic pressure and levels of C-reactive protein（CRP）

D-dimer（DD）

tumor necrosis factor（TNF）

fibrinogen（FIB） and IL-38 between the 2 groups were statistically significant（P<0.05）.The results of correlation analysis showed that IL-38 levels in the 2 groups were significantly negatively correlated with FIB levels（r=-0.305

P=0.015）

and the IL-38 levels in the 2 groups were also significantly negatively correlated with CRP levels（r=-0.396

P=0.028）.Multifactorial logistic regression showed that elevated DD levels and decreased IL-38 levels were risk factors for the development of pulmonary embolism in primary lung cancer（P<0.05）.The area under the ROC curve for serum IL-38 to predict the development of pulmonary embolism in primary lung cancer was 0.726（95%CI:0.647-0.851

P=0.014）

and the sensitivity was 0.742 and the specificity was 0.625 when the serum IL-38 level was at the optimal threshold（51.7 ng/L）.Conclusion IL-38 may improve the status of lung cancer patients by inhibiting the inflammatory response of the body

which in turn leads to a reduced risk of pulmonary embolism

and serum IL-38 levels are predictive of pulmonary embolism in primary lung cancer.