Thyroid transcription factor-1 expression is significantly associated with mutations in exon 21 of the epidermal growth factor receptor gene in Chinese patients with lung adenocarcinoma

Objective: The aim of this retrospective study was to investigate the relationship between thyroid transcription factor-1 (TTF-1) expression and epidermal growth factor receptor (EGFR) gene mutations in lung adenocarcinomas of Chinese patients. Methods: There were 200 lung adenocarcinoma patients who were enrolled in this study. Tumor specimens of these patients were investigated for TTF-1 expression and mutations in EGFR using immunohistochemistry and a liquid chip platform for DNA analysis of slides with sections of formalin-fixed, paraffin-embedded specimens. Results: The rates of TTF-1 expression and EGFR mutations were 81.5% and 45.5%, respectively, in the lung adenocarcinoma specimens of the recruited patients. Among female nonsmokers (n=72), 93.1% of specimens were positive for TTF-1 expression, and 63.9% had EGFR mutations. Of 89 patients with EGFR mutations, 83 (50.9%) specimens were simultaneously positive for TTF-1 expression. Kaplan-Meier analysis of all patient specimens found that postoperative survival time was not significantly associated with TTF-1 expression and the presence of EGFR mutations. However, patients with disease stages III-IV whose tumors were positive for TTF-1 expression and EGFR mutations had better postoperative survival than similar patients whose tumors were negative for TTF-1 expression and EGFR mutations. Conclusion: Our study showed a significant association between TTF-1 positivity and the presence of EGFR mutations (exon 21) in the Chinese lung adenocarcinoma patients. We further identify that patients with disease stages III-IV who were positive for TTF-1 expression and EGFR mutations had a better postoperative survival than those patients who were negative for TTF-1 expression and EGFR mutations. Therefore, TTF-1 might be a potential prognostic biomarker for stages III-IV lung adenocarcinoma patients. In clinical practice, TTF-1 expression may be a marker for planning therapy for certain patients with lung adenocarcinoma, especially for selection of EGFR tyrosine kinase inhibitors.