The Study Of The Circulating Mutational Portrait Of Malignant Tumor

Objective: The presence of solid tumors in tissues and organs through circulating tumor cell(CTC)and circulating tumor DNA(ct DNA)will leave footprints in the circulatory system.The comparison of ct DNA and tumor DNA mutations can reveal information about the genetic variation of the solid tumor that has been achieved through invasive methods in traditional techniques.Content: Cancer genome sequencing studies have shown that tumors are heterogeneous and have heterogeneity.Biopsy as a standard means of diagnosis of cancer,providing materials for genotyping,can help diagnose and target cancer.However,the biopsy has limitations in the genotyping,evolution,progression,prognosis and heterogeneity of the tumor.The ct DNA is a single or double-stranded DNA released into the blood by tumor cells,which contains mutations in the primary tumor.In recent years,the study of ct DNA analysis based on liquid biopsy provides a new clue for the molecular diagnosis and treatment of cancer.The study found that using ct DNA to screen gene mutations was highly sensitive and could improve the current tumor diagnosis system and facilitate early detection.In addition,ct DNA analysis can accurately determine tumor progression,prognosis,and assisted individualized treatment.Methods: We collected 177 tumor patients,103 cases of patients with lung cancer and other solid tumor patients,74 cases with early and late stage cancer patients from June 2015 to September 2016,Wake Forest Cancer Center(Wake Forest Baptist Comprehensive Cancer Center,NC,US).Among them,37 lung cancer patients were collected blood samples and matched tissue samples.Five lung cancer patients collected blood samples at two different time points.Collected the clinical data of 177 patients at the same time,the social demographic and clinical data including: gender(male,female),age(< 55、55~65、65.1~65、75.1~90),body mass index BMI(underweight,normal,overweight,obesity,smoking history,recent/current smokers,former smokers,never smokers),race(white,black,asian and others),tumor stage(stageⅠ,stageⅡ,stageⅢ,stageⅣ,unknown clinical stage),metastasis sites(0,1,2,3 +),tumor type,vital status of patients(live,death)and the survival time of follow-up.Further separation and extraction ct DNAs in the patients’ blood,and then sequenced by Guardant360 test,identified 73 genetic mutated genes associated with tumor occurrence,development,and analyze the correlation of these drive gene mutation load with clinical features of patients.To quantify the ct DNA somatic mutation of each patient in their blood.Wilcoxon rank sum test and kruskal-wallis test were used to compare the relationship between mutation load and clinical variables in single group and multigroup.Fisher’s exact test was used to determine the relationship between smoking status(current/recent smokers,former smokers,never-smokers)and DNA damage genes.The survival analysis was estimated by kaplan-meier method,and the overall survival rate was evaluated by log-rank test.All tests have both sides,and the test level α =0.05.37 cases of lung cancer cases have the tumour tissue DNA sequencing by Foundation One platform,and analyses the main cloned analysis to compare ct DNA mutations in plasma and tissue mutations in tumor tissue,to evaluation of solid tumors in cloning expression features of circulation.For 5 lung cancer cases have two different time points before and after treatment of gathering ct DNA in the tumor progression and monitoring treatment response.Analysis the same patients before and after treatment in ct DNA changes,to evaluate tumor gene mutations change and treatment response in the process of tumor progression.Results: Mutations in TP53,KRAS,and EGFR genes are most prevalent in our cohort.Mutation rates of ct DNA are similar in early(I and II)and late stage(III and IV)cancers.Mutation in DNA repair genes BRCA1,BRCA2,and ATM are found in 18.1%(32/177)of cases.Patients with higher mutation rates had significantly higher mortality rates.Lung cancer of never smokers exhibited significantly higher ct DNA mutation rates as well as higher EGFR and ERBB2 mutations than ever smokers.Comparative analysis of ct DNA and tumor DNA mutation data from the same patients showed that key driver mutations could be detected in plasma even when they were present at a minor clonal population in the tumor.Mutations of key genes found in the tumor tissue could remain in circulation even after frontline radiotherapy and chemotherapy suggesting these mutations represented resistance mechanisms.Longitudinal sampling of five lung cancer cases showed distinct changes in ct DNA mutation portraits that are consistent with cancer progression or response to EGFR drug treatment.Conclusions: This study indicated that mutations in ctDNA may be an early detection tool for cancer.The ct DNA mutation rate of key tumor related genes was associated with smoking status and mortality.This study quantitatively confirmed the results of ct DNAs circulating in the blood circulation,and revealed the propagation of malignant tumor clones and the survival of drug-resistant clones.Mutations in key genes in tumor tissues remain in circulation,even after first-line chemoradiotherapy,suggesting that these mutations represent an antagonistic mechanism.This unprecedented understanding of tumor heterogeneity and cloning in circulation provides important information for the development of tumors.The study supports the use of ct DNA analysis as a less invasive way to monitor progress in cancer and to choose drugs for cancer evolution.