Effect Of EGFR Mutation Status On The Pattern Of First Local Recurrence After Operation For Stage Ⅲ-N2 Non-small Cell Lung Cancer

BackgroundIn recent years,postoperative adjuvant chemotherapy has become the standard treatment after radical resection of locally advanced non-small cell lung cancer(LANSCLC).However,the incidence of local recurrence and distant metastasis is still high even with postoperative chemotherapy.The control of local recurrence and distant metastasis is the key to the treatment of LANSCLC.Epidermal growth factor receptor(EGFR)tyrosine kinase inhibitor(TKIs)is an important method for the patients of advanced positive EGFR mutation non-small cell lung cancer(NSCLC).Recently,severl studies showed that TKIs can significantly improve the progression-free survival(PFS)of postoperative stage Ⅲ-N2 NSCLC patients.Distant metastasis sites and prognosis were different in stage Ⅲ-N2 NSCLC patients with different status of EGFR mutation.Understanding the influence of EGFR mutation status on PFS and local recurrence pattern in patients with Ⅲ-N2 stage NSCLC after postoperative adjuvant chemotherapy can provide a basis for clinicians to judge the prognosis.ObjectiveThe purpose of this study was to analyze the clinical characteristics of EGFR gene mutation in patients with Ⅲ-N2 stage NSCLC,and whether the status,subtype and abundance of EGFR mutation were related to postoperative PFS and local recurrence pattern in patients with Ⅲ-N2 stage NSCLC.Materials and methodsPatients who received radical resection in the Affiliated Cancer Hospital of Zhengzhou University from 2012 to 2018 were retrospectively reviewed in this study.Patients with stage Ⅲ-N2 non-small cell lung cancer(NSCLC)confirmed by pathology underwent 2-4 cycles of postoperative adjuvant chemotherapy.The general clinical features of EGFR gene mutation were analyzed,including age,sex,location of primary tumor,N2 jump metastasis,tumor size > 5cm and T stage;and the effects of EGFR mutation status,mutation subtype and mutation abundance on PFS and local recurrence pattern.The local recurrence rate of each subgroup was compared with Chi-Squared test and Fisher exact test,the survival curve was analyzed by Kaplan-Meier method,and the differences between groups were compared by Log-rank test.P<0.05 was statistically significant.Results1.A total of 221 patients were included,including 116(52.5%)patients with EGFR mutation,105(47.5%)patients with wild-type EGFR mutation.The EGFR mutation rate in female patients,tumor diameter≤5cm were significantly higher than those in male patients,tumor diameter > 5cm,and the smaller the T stage,the higher EGFR mutation rate.2.The median PFS of patients with EGFR mutation was 31 months,and that of patients without EGFR mutation was 20 months.However,different EGFR mutation subtypes and different mutation abundance had no significant effect on PFS.3.Most of the patients without EGFR mutation recurred in stump(24.1%),supraclavicular region(31%),ipsilateral region 4(25.9%),contralateral region 4(32.8%)and region 7(22.4%),while patients with EGFR mutation mostly relapsed in Objective ipsilateral region 4(23.2%),contralateral region 4(23.2%)and region 7(19.6%).The recurrence rate of stump and supraclavicular region in patients without EGFR mutation was significantly higher than that in patients with EGFR mutation(24.1% vs.8.9%,31% vs.5.3%,all P < 0.05).In the analysis of EGFR mutation subgroup,there was no significant difference in the location of local recurrence between Ex19del and L858 R patients.In the subgroup analysis of different mutation abundance,there was no significant difference in the location of local recurrence among low,moderate and high abundance patients(all P > 0.05).ConclusionThe prognosis of patients with stage Ⅲ-N2 NSCLC after radical resection were different berween positive EGFR mutattion and wild-type EGFR mutation.The first local recurrence sites were different in Ⅲ-N2 stage NSCLC patients with different EGFR mutation status after radical resection.The relapsed rate of stump and supraclavicular lymph nodes in patients with wild-type EGFR mutation of stage Ⅲ-N2 stage NSCLC were more than those with positive EGFR mutation.The prognosis and local recurrence of patients with Ⅲ-N2 stage NSCLC can be predicted according to the status of EGFR mutation.