The Presence of Mutations in Epidermal Growth Factor Receptor Gene Is Not a Prognostic Factor for Long-Term Outcome after Surgical Resection of Non-Small-Cell Lung Cancer

Background: The presence of mutation in EGFR gene is known as a predictive marker for the response to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) treatment. However, whether or not these EGFR mutations are prognostic factors for non-small-cell lung cancer (NSCLC) is debatable. Methods: We retrospectively collected a series of samples from patients whose EGFR mutation status had been tested, and analyzed their survival. The pathologic cell types of 863 patients (520 men, 343 women) were squamous cell carcinoma in 227, adenocarcinoma in 636 patients. Results: EGFR mutations were detected in 354 patients and it was frequently observed in adenocarcinoma in younger, early-stage, female never-smokers. In univariate analysis of younger, early-stage, never-smoker women, bronchioloalveolar carcinoma pattern and the presence of EGFR mutation showed better long-term survival. However, in multivariate analysis, age, pathologic stage, and smoking status remained significant prognostic factors, whereas EGFR mutation was not. For recurrence, pathologic stage was the only independent prognostic factor. After recurrence, smoking status was the only significant risk factor that affected postrecurrence survival. However, when EGFR TKIs were used in EGFR-mutated patients, survival was longer than for those treated with conventional chemotherapy. Conclusions: Although the EGFR mutation is a predictive marker for EGFR TKI response, it is not a prognostic factor in NSCLC. The clinical observation that patients with EGFR mutation seem to survive longer may be because EGFR mutation is more frequently associated with other good prognostic factors. Once there is a recurrence, administration of EGFR TKI for patients with EGFR mutation may increase survival.