Comparison Of EGFR Gene Mutations Among Plasma CtDNA、Primary Tumor And Metastatic Lymph Nodes In Patients With Lung Adenocarcinoma

Background:Lung cancer is the leading cause of cancer deaths worldwide,while nonsmall cell lung cancer is accounted for nearly about 80% of the above.Non-small cell lung cancer can be divided into different histological types, including adenocarcinoma, squamous cell carcinoma, neuroendocrine carcinoma,adenoid squamous cell carcinoma,sarcoma like cancer,etc. Adenocarcinoma can be accounted for more than 50%. In tumorigenesis, survival and proliferation process, it needs to aberrant molecular signal which can continue to play a role. This kind of abnormal signal molecules is known as driven oncogene, so the cancer gene can be as a therapeutic target.The application of targeted drugs which can specificly kill tumor cells and does not damage normal cells. The mutation rate of EGFR gene is about 51.2% in the Asian lung adenocarcinoma population, and the efficiency of targeted therapy in patients with EGFR gene mutation was more than 80%. But for advanced non-small cell lung cancer patients, because of the difficulty of obtaining tissue samples, it can not detect EGFR gene mutations in those patients easily,then it is not certain whether the application of targeted drugs will benefit the patients. Ct DNA is a tumor marker that exfoliated tumor cells or apoptosis tumor cells release DNA into the circulation. Therefore, by detecting the EGFR gene mutations in ct DNA can reflect the gene mutation of the tumor, which can be used to instruct the clinical in application of molecular targeted drug therapy for lung adenocarcinoma patients.Methods:Lung adenocarcinoma patients detect EGFR gene mutation status in primary tumor and metastatic lymph node, ct DNA applied with ARMS, to compare the consistency among the ct DNA、primary tumor and metastasis lymph nodes EGFR gene mutations before the operation, to preliminary exploration of the feasibility of application of ct DNA in lung adenocarcinoma patients with EGFR gene mutations detection.Results: 1. The proportion of female with EGFR mutations in adenocarcinoma was higher than that in male, and the percentage of EGFR mutation in patients who never smoking was higher than that in the patients with smoking history. Age, primary tumor size, lymph node stage and TNM stage had no significant difference in the positive rate of EGFR mutation. 2. For patients with primary tumor EGFR mutation positive, using Kappa test,primary tumor and ct DNA in EGFR gene mutation Kappa value =0.789, P < 0.001; metastatic lymph nodes and ct DNA in EGFR gene mutation Kappa value =0.743, P < 0.001. 3. For patients with primary tumor EGFR mutation negative, the primary tumor and ct DNA EGFR gene mutation type consistency was 87.5%; metastasis lymph nodes and ct DNA in EGFR gene mutation type consistency Kappa value =0.634, P < 0.001. 4. For all into the group of adenocarcinoma patients data was analyzed using Kappa test.The primary tumor and metastatic lymph nodes of EGFR gene mutation Kappa value =0.685, P < 0.001; primary tumor and ct DNA in EGFR gene mutation type Kappa value =0.812, P < 0.001; metastatic lymph nodes with ct DNA EGFR gene mutation Kappa value =0.816, P < 0.001.Conclusions: 1. In lung adenocarcinoma patients, the positive rate of EGFR gene mutation in female and never smokers were higher than that in male and in patients with smoking history. 2. Plasma ct DNA with primary tumor samples and metastatic lymph node samples in EGFR gene mutations have a high consistency(81.2%, 81.6%,p<0.001). In non-small cell lung cancer population,it can reflect a majority of tumor gene mutation by detecting EGFR gene mutation in ct DNA.