Clinical Application Of EGFR Gene Mutation Detection In Patients With Lung Adenocarcinoma

Objects: 1.To compare the efficacy and evaluate clinical value of amplification refractory mutation system PCR(ARMS-PCR)and SuperARMS-PCR detection systems in detection of epidermal growth factor receptor gene mutations in paraffin-embedded tumor tissues and plasma circulating tumor DNA(ctDNA).2.To detect the EGFR gene mutation in plasma ctDNA in patients with advanced lung adenocarcinoma by using the chip-based digital PCR technique,and to explore the feasibility of the clinical application of the chip-based digital PCR in the detection of EGFR gene mutation.Methods: 1.Inclusion of 10 patients diagnosed as lung adenocarcinoma at the Affiliated Hospital of North Sichuan Medical College from July 2017 to January 2018.The ARMS-PCR and SuperARMS-PCR detection systems were used to detect the plasma ctDNA and EGFR gene mutations in tumor tissues,and to evaluate the effectiveness of the two detection systems for the detection of EGFR gene mutations.2.Inclusion of 26 cases from July 2017 to December 2017 at the Affiliated Hospital of Northern Sichuan Medical College and diagnosed as stage III~IV lung adenocarcinoma patients according to the eighth edition.Using chip-based digital PCR technology to detect the EGFR gene mutation in plasma ctDNA,combined with its clinical data to explore the potential clinical value of digital PCR.Results: 1.The ARMS-PCR method was used to detect EGFR gene mutations in 10 paraffin-embedded tumor tissues.Three cases of gene mutations were found in the tumor tissues,including 19 del in 1 case and L858 R in 2 cases.The positive detection rate was 30%(3 /10);Only 1 case of the EGFR gene mutation was detected in the 10 plasma samples paired with the tissue.The mutation type was L858 R mutation.The positive detection rate was 10%(1 /10).The type of mutation detected was the same as the paired tissue mutation type.2.SuperARMS-PCR was used to detect EGFR gene mutations in 10 paraffin-embedded tumor tissues.The results showed that there were 7 cases of gene mutations,including 4 cases of 19 del mutation,2 cases of L858 R mutation,and 1 case of 19 del and L858 R double mutations,and the positive detection rate was 70%(7 /10).A total of 3 EGFR gene mutations were detected in 10 plasma samples matched with tissues,the positive detection rate was 30%(3 /10).Among them,2 of these mutations were 19 del,and the type of mutation detected was the same as that of their paired tissue mutations.The other case was the L858 R mutation,and no mutation detected in paired tumor tissue.3.In paraffin-embedded tumor tissues,SuperARMS-PCR method had higher detection rate of EGFR gene mutation than ARMS-PCR method(70% v.s 30%).In plasma specimens,SuperARMS-PCR method also has a higher EGFR gene mutation detection rate than ARMS-PCR method(30% v.s 10%).Using the SuperARMS-PCR method for detecting EGFR gene mutations in EGFR gene mutations as a reference method,the detection rate of plasma EGFR gene mutation by ARMS-PCR was 10%,the sensitivity was 14.2%,the specificity was 100%,and the positive predictive value was.100%,negative predictive value of 28.6%.The detection rate of plasma EGFR gene mutation by SuperARMS-PCR was 30%,the sensitivity was 28.6%,the specificity was 66.6%,the positive predictive value was 66.6%,and the negative predictive value was 28.6%.4.By analyzing the length of the ctDNA extracted by the nucleic acid extraction reagent used by the ARMS-PCR method,it was found that they were mostly small fragments of 100 bp or less.5.The ctDNA EGFR gene mutation in 26 patients with pathologically confirmed advanced lung adenocarcinoma was detected by chip-based digital PCR.The results showed that there were 6 cases of mutations,the mutation rate was 23.1%,including 2 cases of 19 del mutation and 3 cases of L858 R mutation,and one case is the double mutation of 19 del and L858 R.6.The influence of age,sex,smoking history,and disease stage on plasma EGFR mutation status was analyzed in 26 patients with advanced lung adenocarcinoma.The results showed that there was no statistical difference in the detection rate of EGFR gene mutations with patients' sex,age,and smoking history(P>0.05),and tumor stage was related to EGFR mutation status(P<0.05).Conclusions: 1.Plasma detection can be used as a rapid detection method for the EGFR gene mutation status in patients with lung adenocarcinoma,and its positive result can be used as a confirmatory result for targeted drug use.Negative results of plasma EGFR gene mutation detection need to obtain tumor tissue for verification.2.SuperARMS-PCR method has higher detection rate and sensitivity of EGFR gene mutation than ARMS-PCR method,and it is more suitable for the clinical detection of EGFR gene mutation,especially the clinical detection of plasma ctDNA specimen.3.The extraction efficiency of the cell-free nucleic acid extraction kit has an impact on the detection rate of plasma ctDNA EGFR gene mutations.4.Chip-based digital PCR can quantitatively analyze plasma ctDNA EGFR gene mutations,and its clinical applications still needs further verification.5.The detection rate of plasma ctDNA EGFR gene mutation in patients with advanced lung adenocarcinoma is related to the patient's tumor stage.