Circulating DNA EGFR Mutation And The Targeting Therapy Response In Advanced NSCLC Patients

Objective: To screen EGFR mutation in serum circulating DNA and compared with that in tumor tissue.Analysis the consistency of two kinds of tests for verifying the possibility of the EGFR mutationsdetermination in circulating DNA. Combined with clinical data for analysis of the clinical distribution ofadvanced NSCLC patients with EGFR mutations and the evaluation of relationships between EGFRmutation and the targeted drug efficacy. Offer a more convenience, quicken and noninvasive moths ofEGFR gene test for patients with advanced NSCLC.Methods: From September2011to September2012, Shihezi University School of Medicine, FirstAffiliated Hospital of advanced NSCLC patients,48cases with EGFR TKIs therapy experience werecollected for serum and tumor tissue supply. The EGFR mutation status was re-evaluated by directsequencing. The clinical outcomes of EGFR TKIs were analyzed by SPSS17.0Results:1. The detection rate of EGFR mutation in48serum tissue is14.6%(7/48),57.1%(4/7) of which is19exon mutation and42.9%(3/7) is21exon mutation. While the detection rate of EGFR mutation in48tumortissue is31.2%(15/48),60.0%(9/15) of which is19exon mutation and40.0%(6/15) is21exon mutation.The mutation types detected in the study are19DelK746-A750,19DelK745-E749,19DelK745-A750of19exon mutation, and21L858R,21L861Q of21exon mutation.2. In study, EGFR mutation are liable to be detected in women and non-smokers(P<0.05). There is nodifference between test in tumor tissue or serum.3. Compared with the tumor tissue samples, the specificity of the EGFR gene mutation detection inserum samples was97%and sensitivity of it was40%. Coincidence rate of two samples was79.2%(38/48).There are certain consistency between Serum and tomer tissue for detection of EGFR mutations (Kappa=0.433, P<0.05)4.The objective response rate and disease control rate of16positive patients was significant,50.0%(8/16) and75.0%(12/16), and that was15.6%(5/32) and31.2%(10/32) of32positive patients.Following-up until March2013, the PFS was34-359days, and the median PFS was89days. The PFS ofpositive type was obviously superior to the wild type patients(χ2=11.287, P=0.001).Conclusion:1.Serum circulating DNA can be used for EGFR gene mutation detection, monitoring targeted therapyefficacy of lung cancer, optimizing individualization treatment of the advanced lung cancer. However, it hascertain false negative rate, so we need higher sensitivity test methods.2.EGFR gene mutations are mainly distributed in women and non-smokers.3.Advanced NSCLC patients of EGFR gene mutation type are more likely to benefit from treatment ofEGFR TKIs.