P1.08-035 Analysis of Post-Operative Recurrence in a Population with NSCLC Harboring an EGFR Mutation: A Single Institutional Retrospective Study

Abstract

The post-operative recurrence in the patients resected EGFR mutated NSCLC was higher than wild-type, as previous reported. However, whether EGFR mutational status is prognostic factor or not had not been yet proven, and we assessed the background of the patients with surgically resected NSCLC harboring EGFR mutation and the post-operative clinical course. We reviewed all patients with EGFR mutated NSCLC who received surgical therapy for lung cancer between March 2007 and April 2016 at Matsusaka Municipal Hospital in order to assess post-operative recurrence and overall survival retrospectively. Survival curves of time to post-operative recurrence and overall survival were calculated using the Kaplan-Meier method and were compared using the log-rank test. Subgroup analyses were conducted to evaluate predictive factors for post-operative recurrence. A total of 116 patients were enrolled. The median age was 72.5, ranging from 37-88 years of age. Of the total, 83 patients (71.6%) were female, and 90 patients had never smoked. All patients except one with squamous cell carcinoma were diagnosed pathologically with adenocarcinoma. Of the patients 41.9% were diagnosed with Ex19 deletion and 50.0% were diagnosed with Ex21 L858R. Median time to post-operative recurrence was 70.5 months for the entire population. Multivariate analysis revealed that age (p=0.008), subtype of EGFR mutation (p=0.034), and pathological stage (p=0.00033) were predictive factors for post-operative recurrence. Subgroup analysis revealed there was a significant difference in time to post-operative recurrence between patients over 75 y.o and those under 74 y.o even in the population who received a lobectomy. (p=0.031). Elderly patients, and those with the Ex21 L858R point mutation, had a tendency to relapse after surgical therapy among the EGFR mutated NSCLC population. The rate of post-operative recurrence in EGFR mutated patients tended to be higher compared to historical data. Because of differences with retrospective data and the small sample size, further investigations are warranted to confirm these results.