Long-term follow-up of a consecutive cohort validating an epidermal growth factor receptor mutation as an independent risk factor for postoperative recurrence in lung adenocarcinoma

OBJECTIVES: Third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors were recently reported to be effective as adjuvant therapy for resected lung adenocarcinoma (ADC) harbouring common EGFR mutations. However, whether the EGFR mutation is a direct risk factor for postoperative recurrence remains unknown. Therefore, we conducted a multi-institutional observational study to compare postoperative survival according to EGFR mutation status.METHODS: We collected the medical records of consecutive patients who underwent surgical resection for ADC between 2005 and 2012 at 4 participating institutions. Recurrence-free survival (RFS) and overall survival (OS) associated with EGFR mutation status were evaluated. We further analysed survival after pair-matching patients' clinicopathological characteristics.RESULTS: EGFR mutations were harboured by 401 of 840 (48%) enrolled patients. The number of patients with an EGFR mutation (M group) differed from that with the EGFR wild-type sequence (W group) in terms of sex, smoking history and pathological stage. The median follow-up period was 85 months. The five-year RFS/OS rates of the M and W groups were 70%/85% and 61%/75%, respectively (P < 0.001 for both groups). However, multivariable analysis revealed that EGFR mutation status was not independently related with both RFS and OS. In pair-matched analysis, the RFS and OS curves of the patients with an EGFR mutation and wild-type sequence were not statistically different, either.CONCLUSIONS: Long-term follow-up of consecutive patients did not show that a common EGFR mutation was an independent risk factor of recurrence or prognostic factor for completely resected lung ADC.