Abstract:

Objective To investigate the changes of serum bile acid spectrum in patients with lung cancer and its value in the differential diagnosis of pneumonia and lung cancer. Methods Serum bile acid spectrum of 80 patients with pneumonia（pneumonia group）,108 patients with lung cancer（lung cancer group） and 106 healthy subjects（healthy control group） were determined by liquid chromatography-tandem mass spectrometry（LC-MS/MS）,including 5 free bile acids [cholic acid（CA）,chenodeoxycholic acid（CDCA）,deoxycholic acid（DCA）,lithocholic acid（LCA）,ursodeoxycholic acid（UDCA）] and 10 conjugated bile acids [glycocholic acid（GCA）,glycochenodeoxycholic acid（GCDCA）,glycodesoxycholic acid（GDCA）,glycolithocholic acid（GLCA）,glycoursodeoxycholic acid（GUDCA）,taurocholic acid（TCA）,taurochenodeoxycholic acid（TCDCA）,taurodeoxycholic acid（TDCA）,taurolithocholic acid（TLCA）and tauroursodeoxycholic acid（TUDCA）]. Serum total bile acid（TBA） and tumor markers,such as carbohydrate antigen（CA） 125,CA19-9,carcinoembryonic antigen（CEA）,cytokeratin 19 fragment（CYFRA 21-1） and neuron specific enolase（NSE）,were also determined. Logistic regression was used to screen items,and the diagnosis model was established. Receiver operating characteristic（ROC） curve was used to analyze the performance of these items and diagnosis model in the differential diagnostic of pneumonia and lung cancer. Results Compared with healthy control group,the levels of DCA,LCA,UDCA,GDCA,GLCA,TDCA,and TLCA decreased in pneumonia group（P<0.01）,while GCDCA and TCDCA increased（P<0.01）; CA,CDCA,GCDCA,and TCDCA increased in lung cancer group（P<0.01）,while TDCA and TLCA decreased（P<0.01）. There was no statistical significance in the level of serum TBA among the 3 groups（P>0.05）. The levels of CA,CDCA,DCA,LCA,UDCA,GDCA,GLCA,CEA,and CYFRA21-1 in lung cancer group were significantly higher than those in pneumonia group（P<0.01）. ROC curve analysis showed that DCA had the best performance in the differential diagnosis of pneumonia and lung cancer among all the single items [the area under curve（AUC） of 0.781,the sensitivity of 73.2%,the specificity of 77.5% and the Youden index of 0.51]. The diagnosis model had good performance with the AUC of 0.873,the optimal cut-off value of 0.52,the sensitivity of 89.3% and the specificity of 75.4%. Conclusion The changes of bile acid spectrum are closely associated with the occurrence of lung diseases. Bile acid spectrum is potential as diagnostic markers for lung cancer.

Key words: Bile acid spectrum, Tumor marker, Liquid chromatography-tandem mass spectrometry, Lung cancer, Pneumonia