Thyroid transcription factor-1 as a prognostic indicator for stage IV lung adenocarcinoma with and without EGFR-sensitizing mutations

Abstract Background Thyroid transcription factor (TTF)-1 expression is a diagnostic marker and a good prognostic indicator for lung adenocarcinoma. However, its good prognostic ability might be due to epidermal growth factor receptor (EGFR)-sensitizing mutations as shown by the positive correlation between TTF-1 expression and EGFR mutations. We explored the prognostic impact of TTF-1 expression according to EGFR-sensitizing mutation status in lung adenocarcinoma patients. Methods We conducted a retrospective cohort study of patients with stage IV lung adenocarcinoma. Data were extracted from the lung cancer registry of Hallym University Medical Centers (three hospitals) in Korea between March 2006 and March 2016. Results Overall, 173 patients were included. EGFR-sensitizing mutations were detected in 84 (51.4%) patients. TTF-1 expression was positive in 139 (80.3%) patients; it was significantly correlated with EGFR-sensitizing mutations (p