EGFR mutations in early‐stage and advanced‐stage lung adenocarcinoma: Analysis based on large‐scale data from China

BACKGROUND: EGFR‐tyrosine kinase inhibitors play an important role in the treatment of advanced non‐small cell lung cancer (NSCLC). EGFR mutations in advanced NSCLC occur in approximately 35% of Asian patients and 60% of patients with adenocarcinoma. However, the frequency and type of EGFR mutations in early‐stage lung adenocarcinoma remain unclear. METHODS: We retrospectively collected data on patients diagnosed with lung adenocarcinoma tested for EGFR mutation. Early stage was defined as pathological stage IA–IIIA after radical lung cancer surgery, and advanced stage was defined as clinical stage IIIB without the opportunity for curative treatment or stage IV according to the American Joint Committee on Cancer Staging Manual, 7th edition. RESULTS: A total of 1699 patients were enrolled in this study from May 2014 to May 2016; 750 were assigned to the early‐stage and 949 to the advanced‐stage group. Baseline characteristics of the two groups were balanced, except that there were more smokers in the advanced‐stage group (P < 0.001). The total EGFR mutation rate in the early‐stage group was similar to that in the advanced‐stage group (53.6% vs. 51.4%, respectively; P = 0.379). There was no significant difference in EGFR mutation type between the two groups. In subgroup analysis of smoking history, there was no difference in EGFR mutation frequency or type between the early‐stage and advanced‐stage groups. CONCLUSION: Early‐stage and advanced‐stage groups exhibited the same EGFR mutation frequencies and types.