Predictive Value Of Exhaled Breath VOCs On Pulmonary Nodule In People Less Than 50 Years Old

Research background and purpose:According to the global cancer statistics in 2018,the morbidity and mortality of lung cancer are in the first places among all malignant tumors respectively.Although the 5-year survival rate of patients with early diagnosis of lung cancer can reach 70%-90%,the 5-year survival rate of patients with advanced lung cancer is only 12%.Therefore,the early diagnosis of lung cancer is the key to successful treatments.At present,the most commonly used clinical screening method for lung cancer is low-dose spiral CT(low-dose CT,LDCT).It can improve the diagnosis rate of early lung cancer and reduce the mortality of lung cancer to some extent.In China,LDCT has been used to screen lung cancer in high-risk people over 50 years old.With the widespread using of LDCT,more and more pulmonary nodules are found in young and middle-aged people.In the follow-up of pulmonary nodules,LDCT may not only cause the unnecessary radiation injury,but also increase the psychological burden and the economic burden of patients or society.In summary,there is an urgent need for a rapid,sensitive and non-invasive method to differentiate the malignant tumor from the benign in young and middle-aged people with pulmonary nodules.Metabolites,such as volatile organic compounds(volatile organic compounds,VOCs)in the human body,can reach the lung through the blood,where substances are exchanged and removed from the body through the respiratory tract.Therefore,exhaled VOCs can reflect the state of the bodily disease.Exhaled VOCs is a non-invasive,rapid and repeatable index,which is expected to be a powerful means to assist the early diagnosis of lung cancer.Exhaled VOCs has been used in the diagnosis of lung cancer for more than 30 years.A large number of studies have shown that VOCs has great potential in the early diagnosis of lung cancer.However,in the published studies,the age of the lung cancer group does not match that of the control group.The age of patients in the lung cancer group is usually significantly older than that of the control group,and the average age is more than 50 years old.At the same time,most of the studies selected healthy people as the control group,while a few studies took patients with different degrees of chronic obstructive pulmonary disease with emphysema and chronic bronchitis as the control group at the same time.At present,there is a lack of special research on young and middle-aged people and specific space-occupying lesions in the lungs.In this study,patients under 50 years old with pulmonary nodules were selected as subjects to explore the ability of VOCs to predict the benign and malignant pulmonary nodules in young and middle-aged people.Research Methods:In this study,patients under 50 years old with definite pulmonary nodules in CT were divided into lung cancer group and benign lung disease group according to the pathological results,and finally included 104 patients with lung cancer and 43 patients with benign pulmonary diseases.The clinical characteristics and exhaled breath of the subjects were collected,and the exhaled VOCs of the subjects was detected and analyzed by SPME-GCMS method.The clinical characteristics and VOCs of the two groups were compared,and the variables(P<0.1)were included in the univariate Logistic regression analysis,and then the variables(P<0.1)in the univariate regression analysis were included in the multifactor conditional Logistic regression analysis.The predictive model was established to calculate the sensitivity and specificity of the model.The subject working characteristic curve of the prediction model was constructed,and the area under the curve was calculated.At the same time,the VOCs of lung cancer group under different pathological stages,age,gender and smoking status were compared.Result:1.There was significant difference in the detection rate of cyclopentane(P=0.002),3-methylpentane(P=0.043)and ethylbenzene(P=0.009)VOC between lung cancer group and benign lung disease group.There were significant differences in cyclopentane content(P=0.009),gender(P=0.034)and smoking status(P=0.047)between lung cancer group and benign lung disease group.2.A binary Logistic regression prediction model was established with cyclopentane,3-methyl pentane,ethylbenzene,n,n-dimethylformamide and gender as variables.The sensitivity of the prediction model was 80.8%,the specificity was 60.5%,and the area under the working characteristic curve of the subjects was 0.781.3.In lung cancer group,there was only significant difference in the content of dipentene between early lung cancer and middle and advanced lung cancer(P=0.047),and only nonanal in different ages(P=0.025).The content of o-xylene in female was lower than that in male,and the difference was statistically significant(P=0.034),while only cyclopentane was different among different smoking states(P=0.042).Conclusion:1.The exhaled VOCs expression of cyclopentane,3-methylpentane and ethylbenzene in lung cancer patients less than 50 years old was significantly different from that in patients with benign pulmonary diseases.2.The prediction model based on cyclopentane,3-methylpentane,ethylbenzene,n,n-dimethylformamide and gender has a certain ability to predict the benign and malignant pulmonary nodules in people under 50 years old.3.In the lung cancer group,there was no significant difference in the expression of total VOCs in exhaled breath among the subjects with different pathological stages,age,sex and smoking status,but only a few VOC.