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 byimmunohistochemistry and EGFR mutations by DNA direct sequencing. Finally, the correlation between TTF-1 expression and the presence of EGFR mutations was analyzed using χ(2) 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.