The Relationship between TTF-1 Expression and EGFR Mutations in Lung Adenocarcinomas

OBJECTIVE To explore the relationship between TTF-1 and EGFR mutations in lung adenocarcinoma tissues to guide clinical treatment timely and effectively. MATERIALS AND METHODS we collected 664 tissue samples from patients with histologically confirmed lung adenocarcinoma from May 2010 to April 2013. All tumor tissues were collected prior to administering therapy. TTF-1 was detected by immunohistochemistry and EGFR mutations by DNA direct sequencing. Finally, the correlation between TTF-1 expression and the presence of EGFR mutations was analyzed using χ2 test or Fisher's exact test with SPSS software version 18.0. RESULTS Of the 664 lung adenocarcinoma tissue samples, 18 were partially positive for TTF-1 (+-), and 636 were positive for TTF-1 (+) resulting in a total positive rate of 98.49% (+,+-)(including partial positive). In only 10 cases was the TTF-1 negative (-); the negative rate was 1.51%. There were 402 cases without an EGFR mutation and 262 cases with EGFR mutations; the rate of mutations was 39.46%. The location of the EGFR mutation was exon 19 for 121 cases resulting in a mutation rate in exon 19 of 18.22%. The location of the EGFR mutation was exon 21 for 141 cases resulting in a mutation rate in exon 21 of 21.23%. Exon 18 and 20 detected by DNA direct sequencing no mutations.A Fisher's exact test was used to determine the correlation between EGFR mutations and TTF-1 expression.for the whole, TTF-1 positive expression(including partial positive) has correlation with EGFR mutations (p<0.001),especially for Exon 21 expression,the correlation is significant (p = 0.008). CONCLUSION In lung adenocarcinomas, positive and partial positive TTF-1 expression has a significant positive correlation with EGFR mutations(exon 19 and 21). In clinical practice, TTF-1 expression combine with EGFR mutations, especially exon 21 mutation can guide clinical treatment timely for lung adenocarcinomas.