Clinical Study On The Prediction Of EGFR Mutation By PET/CT Before Treatment Of NSCLC And The Value Of PET/CT-guided Targeted Rebiopsy In Patients Treated By EGFR-TKI With Advanced NSCLC

Chapter 1 Clinical study on the prediction of EGFR gene mutation by 18F-FDG PET/CT before treatment of NSCLCObjective:The determination of EGFR gene type before treatment of non-small cell lung cancer plays an important role in the choice of later treatment methods.This study mainly discussed the relationship between 18F-FDG PET/CT related metabolic parameters SUVmax,SUVav and EGFR mutation in non-small cell lung cancer,and analyzed their efficacy in predicting EGFR mutation.Methods:Retrospective analysis was performed on patients with NSCLC who underwent 18F-FDG PET/CT examination and PET/CT-guided targeted biopsy in our department from 2012 to 2019.Combined with SUVmax,SUVav of the biopsy lesion and the clinical characteristics of patients,multivariate regression analysis was performed to screen out the relevant influencing factors that have predictive significance for EGFR mutation in biopsy lesions.Then,the ROC curve was used to analyze the efficacy of SUVmax,SUVav and comprehensive factors in determining the EGFR mutation.Results:A total of 434 patients with non-small cell lung cancer(NSCLC)were included in the study,including 186 patients with EGFR mutation.The results of multivariate regression analysis suggested that the SUVmax value(OR=0.717),smoking(OR=0.052)and pathology type(OR=2.397)of the biopsy lesions were the relevant factors affecting EGFR mutation(P<0.05).The area under ROC curve(AUC)of SUVmax and SUVav were 0.703 and 0.692,respectively.The area under the ROC curve significantly increased(AUC=0.8)after the factors of SUVmax value,smoking and pathological type were considered.The results of threshold analysis of ROC curve showed that the biopsy lesions with SUVmax≤7.3 and SUVav≤4.06 were more likely to have EGFR mutation.Conclusion:The lower SUVmax value may be correlated with EGFR mutation.Combining SUVmax,smoking and pathology type can significantly improve the accuracy of prediction of EGFR mutation.Chapter 2 Clinical study on the value of PET/CT-guided targeted rebiopsy in patients treated by EGFR-TKI with advanced NSCLCObjective:Although targeted therapy for EGFR mutations has brought good prognosis for some patients with NSCLC,the treatment will eventually fail due to a series of drug resistance mechanisms.PET/CT-guided rebiopsy helps to understand this drug resistance mechanism and provide valuable clinical information for subsequent treatment.Methods:We collected patients with advanced non-small cell lung cancer who underwent 18F-FDG PET/CT examination and underwent biopsy and rebiopsy with the assistance of PET/CT from 2012 to 2018.The EGFR gene type after the first PET/CT-guided biopsy,the progression-free survival time after the first EGFR-TKI treatment,the pathology of rebiopsy after drug resistance,the type of gene change after drug resistance and the treatment methods after drug resistance were recorded in detail,and the changes in EGFR and treatment were compared and analyzed.Results:We eventually included 47 patients in the study.The inconsistency rate of gene type and pathology type after EGFR-TKI treatment was 70.21%,of which T790M mutations accounted for 42.55%(20 cases),and c-MET amplification accounted for 6.38%(3(Example),6.38%of patients with small cell lung cancer transformation(3 cases),14.89%of patients with wild type EGFR transformation(7 cases),and 29.79%of patients with unchanged EGFR gene type(14 cases).The overall treatment effective rate after PET/CT-guided rebiopsy was 53.19%(25 cases),and the clinical benefit rate was 70.21%(33 cases).Univariate analysis showed that there was no correlation between progression-free survival after EGFR-TKI treatment and patients’ age,gender,pre-treatment gene type,post-resistance gene type,and the targeted drugs.A comparative analysis of 16 patients who underwent PET/CT rebiopsy and ctDNA testing at the same time found that the missed diagnosis rate of ctDNA testing was 33.33%.Conclusion:In patients with advanced non-small cell lung cancer,the EGFR gene type may change after targeted therapy,leading to the failure of the original treatment regimen.However,rebiopsy for progressive lesions may help to clarify the mechanism of drug resistance,and may provide an effective basis for subsequent clinical treatment changes.