Application Of PAP In Monitoring Of Plasma CfDNA In Advanced Non-small Cell Lung Cancer

Background and purpose:Lung cancer,remaining the main cause of mortality among patients with cancer worldwide Targeted therapy is an important treatment for advanced non-small cell lung cancer,in which epidermal growth factor receptor tyrosine kinase inhibitor(EGFR-TKIs)is the most representative.It is need for EGFR mutation detection before the use of EGFR-TKIs.However,due to limited access to surgical tissue,puncture specimens and other reasons,the tissue EGFR mutation rate is low.Circulating free DNA(cfDNA)in the blood carries the gene mutation information of the primary tumor site,which can substitute tissue to be detected,has the advantages of simplicity,quickness,minimally invasive and real-time advantages.There are various methods to detect genetic alterations in cfDNA,with no standardization.Pyrophosphorylation-activated polymerization(PAP)is an original nucleic acid amplification technique that provides ultra-high sensitivity and specificity by blocking primer to joint pyrophosphorylation and polymerization.This study used PAP to detect EGFR mutations in plasma cfDNA in patients with advanced non-small cell lung cancer,explore the application of PAP in detecting plasma cfDNA in advanced non-small cell lung cancer.Materials and methods:A total of 92 patients who were diagnosed with advanced NSCLC between March 2016 and October 2017 were enrolled in the present study,the mutations of EGFR in cfDNA extracted from the plasma were detected using PAP and ARMS PCR technology.Furthermore,39 EGFR-positive patients were selected to monitor the mutations of EGFR using PAP technology.Access to medical records to collect tissue EGFR mutation test results and the clinical and pathological features.The concordance analysis of the mutations of EGFR involved plasma vs.tumor tissue and PAP vs.ARMS PCR.The relationship between plasma EGFR mutation and clinical diagnosis and treatment also be analyzed.Results:1.No statistical differences in the mutations of EGFR were observed between plasma and tissue(p = 0.092).2.No statistical differences in the mutations of EGFR were observed between PAP and ARMS PCR(p = 0.143).3.Patient characteristics such as age,sex,smoking status,family history,performance status,histology and disease stage have no significant associations with plasma EGFR mutation status.4.The detection rate of the mutations of EGFR in cfDNA was higher in the progressor than in the non-progressor(55.2%vs 18.5%,p<0.001).Conclusion:PAP can be used for detecting the mutations of EGFR in cfDNA,there is no statistical differences in the mutations of EGFR were observed between plasma and tissue,the plasma test is simpler,faster,minimally invasive and real-time,there is no statistical differences in the mutations of EGFR were observed between PAP and ARMS PCR,PAP is more economical than ARMS PCR especially for patients who need dynamic monitoring plasma EGFR mutations.Plasma cfDNA dynamic monitoring is recommended for advanced non-small cell lung cancer patients,from which the patients could obtain prediction of disease progression.In the dynamic monitoring process,it is the prediction of disease progression that the plasma test results from negative to positive or persistent positive,in contrast,plasma test results from positive to negative or persistent negative representative effective treatment.