The Study Of The Application Of Liquid Biopsy In The Diagnosis Of Lung Tumors

objective: With the impetus of precision medicine,liquid biopsy is gradually applied to the clinic.Liquid biopsy is a molecular detection method that can dynamically reflect the occurrence and development of tumors.It has been developed rapidly in the clinical research and practice of lung cancer because of its advantages such as non-invasive,easy to obtain sample and real-time monitoring.The accuracy of liquid biopsy in practical clinical diagnosis needs further verification.The purpose of this study is to explore the application of circulating tumor cells(CTCs)in the diagnosis of lung cancer by comparing CTCs level of patients with lung cancer and benign pulmonary nodules.Methods: From March 2016 to February 2018,we have collected a total of 159 patients with pulmonary nodules were emamined by CT in Sichuan Provincial People's Hospital,and 6 healthy volunteers.There are 159 patients with pulmonary nodules which contain 117 patients with lung cancer and 42 patients with benign pulmonary nodule.The patients with benign pulmonary nodule divided into 29 patients with inflammatory nodule and 13 patients with benign tumor Folate receptor was used as target to detect CTCs in peripheral blood of all samples.The statistical analysis and receiver operating characteristic curve(ROC)were used to assess the sensitivity and specificity of CTCs detection for lung tumor,compared the area under curve(AUC)of CTCsand clinical commonly used tumor markers(neuron specific enolase,carcinoembryonic antigen,cytokeratin 19 fragment,squamous cell carcinoma antigen)to assess their accuracy of identification of pulmonary nodules.Results: In the first part.The CTCs level were statistically different between groups of lung cancer patients with different pathological stages and tumor size(P<0.05).The CTCs level of lung cancer patients with metastatic was significantly higher than that of non metastatic lung cancer patients(P=0.003).There was no significant difference between groups of lung cancer patients with different ages,genders,tumor differentiations and pathological patterns in CTCs level(P>0.05).The CTCs level were statistically different between lung cancer group and healthy group(P=0.015),and there was no statistical difference between the benign pulmonary nodules group and lung cancer group(P=0.763).ROC curve analysis was performed on lung cancer and different control groups.The ROC results between lung cancer and benign pulmonary nodules showed that the AUC value of CTCs level was0.540,Youden index was 0.193,the sensitivity was 81.2% and specificity was 39.1%;The ROC results between lung cancer and pneumonic nodule showed that the AUC value of CTCs level was 0.486,Youden index was0.098,the sensitivity was 65% and specificity was 44.8%;The ROC results between lung cancer and lung benign tumor showed that AUC value of CTCs level was 0.662,Youden index was 0.436,the sensitivity was 74.4% and specificity was 59.2%;The ROC results between lungcancer and healthy showed that the AUC value of CTCs level was 0.793,Youden index was 0.628,the sensitivity was 79.5% and specificity was83.3%.The ROC results showed that the AUC value of CTCs level and tumor markers(CEA,NSE,crfra21-1,SCC)were 0.540,0.524,0.411,0.517 and 0.542.Conclusion: The results of this study showed that the CTCs level was related to tumor stage,tumor diameter and metastasis,which could be used to track the development of lung cancer.The detection of CTCs level in peripheral blood was less accurate for the identification of pulmonary nodules,which containing the detection of CTCs level was inaccurate for the identification of lung cancer and pneumonic nodules,and was accurate for the identification of lung cancer with benign lung cancer and healthy people.objective: As an important epigenetic modification in eukaryotic genomes,DNA methylation plays a vital role in many biological processes including maintenance of normal cellular function,genetic imprinting,embryonic development and cancers in higher organisms.In this study,we analysis plasma circulating free DNA methylation change of early lung cancer,and explore the application of plasma cf DNA methylation in early screening of lung cancer.Methods:We have collected preoperative plasma and corresponding paraffin tissue of 3 patients with early lung cancer and plasma of 3 healthy.The methylation-dependent restriction-site associated DNA sequencing(Methyl RAD)was used to detect cf DNA methylation change of all samples.Results: The plasma cf DNA methylation level was lower than paraffin tissue DNA methylation level of early lung cancer,but the difference between healthy plasma cf DNA was not obvious.There were31363 methylation sites were detected in the plasma cf DNA of the lung cancer patients,which were the same as the paraffin tissue DNA,but different from the cf DNA of healthy.The cluster analysis showed that there was no difference in plasma cf DNA methylation level of the patients and healthy,but there was a significant difference between the groups.KEGG enrichment analysis showed that the 20 signal pathways with the highest concentration including non-small cell lung cancer pathway,which including 35 different methylation sites.In addition to the sites(FHIT,CDKN2 A,RASSF1,TP53 and RARB)which have been reported,30 potential sites,such as RASSF5,ERBB2,ALK and CCND1,can be used as potential sites for diagnosis and screening of lung cancer.Conclusion: The specific cf DNA methylation sites detected by Methyl RAD can be used as a candidate marker for early screening and diagnosis of lung cancer,and lay the foundation for non-invasive biopsy of early lung cancer.