Treatment and survival status of patients with EGFR mutation-positive stage Ⅳ lung adenocarcinoma: five-year follow-up results in the Ordos Area of Inner Mongolia, China

Objective We aimed to determine the epidermal growth factor receptor(EGFR) mutation status and treatment survival of patients with stage Ⅳ lung adenocarcinoma living in the Ordos area of Inner Mongolia, China.Methods EGFR testing and first-line tyrosine kinase inhibitor(TKI) treatment rates of patients with stage Ⅳ lung adenocarcinoma were analyzed from June 2012 to June 2016. Kaplan-Meier survival curves were constructed to compare patients who received different treatment strategies and those harboring different EGFR mutation statuses.Results EGFR testing and mutation rates were 65.60% and 52.90%, respectively, and improved continuously from June 2012 to June 2016. Among patients with EGFR mutations, 38.9% had EGFR 19 del, 48.2% had L858 R, 4.2% had co-existing mutations in exons 19 and 21, and 8.4% had uncommon mutations. The median overall survival(OS) was 29.5, 26.5, and 16.0 months for patients receiving both TKI and chemotherapy, TKI alone, and chemotherapy alone, respectively(P = 0.047). The OS was 26.5 and 30.0 months for patients harboring EGFR 19 del and L858 R mutations, respectively(P = 0.096).Conclusion The high OS rates of stage Ⅳ lung adenocarcinoma patients living in the Ordos area may be attributed to continuous improvements in EGFR testing and first-line TKI treatment rates. In the era of TKIs, chemotherapy for increasing OS times should be emphasized.