The features and prognostic impact of extracranial metastases in patients with epidermal growth factor receptor-mutant lung adenocarcinoma

Aims: We have previously demonstrated that brain metastases were more common among patients with epidermal growth factor receptor (EGFR)-mutant lung adenocarcinoma. However, the association of EGFR mutation and extracranial metastases (ECM) remains inconclusive. In this study, we explored the potential association between EGFR mutation and the risk of ECM. Patients and Methods: Between March 2007 and December 2014, 234 patients were analyzed for the potential association between EGFR mutation and ECM. Statistical Analysis Used: Multivariate Cox regression analysis. Results: There were no associations between the EGFR mutation and metastases in different organs, except for bone. The frequency of EGFR mutation was statistically higher for patients with bone metastases (BMs) at the initial diagnosis (P = 0.039) and at the last follow-up (P = 0.018) as compared to those with wild-type EGFR. In multivariate logistic regression analysis, EGFR mutation significantly increased the risk of BM at the initial diagnosis (P = 0.036). Among those patients without BM at initial diagnosis, 1- and 2-year accumulative rates of subsequent BM were significantly higher in patients with EGFR-mutant disease (P = 0.026). EGFR mutation was an independent risk factor for subsequent BM (P < 0.05). In addition, patients with finial BM and EGFR-mutant disease had longer median survival as compared to those with wild-type disease (P = 0.020). Conclusions: Only BM in patients with ECM was significantly correlated with EGFR mutation during their disease course. EGFR mutation was an independent predictive and prognostic factor for developing BM, which was also a positive predictive factor for overall survival of patients who developed BM