The Study Of The Relationship Between EGFR Gene Mutation Status And The Efficacy Of First-line Chemotherapy In Patients With Advanced Lung Adenocarcinoma

Background: The incidence and mortality of lung cancer are the highest in malignant tumors.Although great progress has been made in the diagnosis and treatment of lung cancer in recent years,the 5-year survival rate of lung cancer is about 18%.According to the pathology,treatment,and prognosis of lung cancer,the WHO divides it into non-small cell lung cancer(NSCLC)and small cell lung cancer(SCLC).NSCLC accounts for 80%-85% of lung cancer.Epidermal growth factor receptor(EGFR)gene is the most common driver gene in NSCLC and its mutation rate is up to 40-50% in Asian patients.Epidermal growth factor receptor tyrosine kinase inhibitor(EGFR-TKI)has become the standard first-line and second-line treatment for advanced NSCLC patients with EGFR mutation,its objective response rate(ORR)and progression free survival(PFS)are superior to standard chemotherapy.EGFR gene status is a predictor of EGFR-TKI,and NSCLC patients with EGFR mutation can benefit from EGFR-TKI.Although molecular targeted therapy is the main therapy for driver gene positive patients,chemotherapy is still indispensable in NSCLC treatment.Previous study have shown that patients with EGFR mutations who received both EGFR-TKI and chemotherapy had the longest overall survival(OS)than that with EGFR-TKI or chemotherapy alone.Moreover,chemotherapy is also the main treatment for EGFR-TKI acquired resistance.For patients with EGFR wild type,chemotherapy is still one of the major of treatments.Problem in clinic is that there has not yet been a clear biomarker for predicting the efficacy of chemotherapy so far.Whether the EGFR gene status can be a predictor of chemotherapy and whether different EGFR mutation have different sensitivity to chemotherapy are needed further explored to achieve individualized chemotherapy.Research purposes: The purpose of this study is to investigate the relationship between epidermal growth factor receptor(EGFR)mutation status and the efficacy of first-line chemotherapy in patients with advanced lung adenocarcinoma.Methods: The 155 patients with stage IIIB or IV lung adenocarcinoma confirmed by histopathology or cytology in General Hospital of Guangzhou Military Command From January 2010 to December 2016 are studied.All the patients were clear with EGFR gene status and had been accepted platinum-based first-line chemotherapy.The relationship between EGFR gene mutation status and first-line chemotherapy response rate(RR)and progression-free survival(PFS)was analyzed.Results: Among 155 patients,90(58.0%)patients were EGFR wild-type and 65(42.0%)patients were EGFR mutation,of which 19(19.4%)were exon 19 mutation and 35(22.6%)were exon 21 mutation.There was no significant difference for the response rate of chemotherapy between EGFR mutation and EGFR wild type(38.5%vs.33.3%,P>0.05).The PFS was evaluated in 102 patients with a median PFS of 5.7months.The PFS of the patients with EGFR mutation was significantly longer than those with EGFR wild type(7.1 months vs.5.0 months,P=0.006).Whether the EGFR gene was mutated or not,there was no significant difference in the RR between the pemetrexed-group and the non-pemetrexed-group(37.0% vs.39.4% in the mutation group,P=0.842,33.3% vs.33.3% in the wild-type group,P=1.000).However,the PFS of patients with pemetrexed-group was significantly longer than that of patients with non-pemetrexed-group(10.1 months vs.5.1 months in the mutation group,P=0.001;5.7 months vs.4.1 months in the wild-type group,P=0.023).In the subgroup analysis,there was no significant difference in the RR of the patients with exon 19 mutation and exon 21 mutation(43.3% vs.34.3%,P=0.455).The PFS of the patients with exon 19 mutation and that patients with exon 21 mutation were similar(6.7months vs.7.4 months,P=0.534).Conclusions: The EGFR gene mutation status of advanced lung adenocarcinoma is not correlated with the response rate of first-line chemotherapy.The PFS of the patients with EGFR mutation is longer than those patients with EGFR wild-type.There is no significant difference in RR or PFS between the patients with exon 19 mutation group and exon 21 mutation group.Regardless of EGFR mutation status,PFS in patients who received pemetrexed-based regimen was significantly longer,which is more significant in patients with EGFR mutation,suggesting that EGFR mutation may be one of indicators for pemetrexed-based regimen.