Evaluation of fgfr1 by immunohistochemistry and fluorescence in situ hybridization (FİSH) in squamous cell lung carcinomas

Lung cancer is the leading cause of cancers related deaths. There are many clinical, pathological and genetic factors that may be effective on the survival and prognosis of patients in lung cancer. Fibroblast growth factor receptor 1 (FGFR1) amplification has recently been described as a genomic aberration identified in various types of cancers, specifically defined as a potentially appropriate target in lung squamous cell carcinoma (SCC). The amplification ratios and prognostic factors of FGFR1 in lung SCC are controversial. In our study, we aimed to determine the prevalance of FGFR1 amplification in our population, to evaluate the association between FGFR1 amplification and clinicopathological parameters of lung SCC and to determine its prognostic significance, as well as the correlation between immunohistochemical FGFR1 expression rate and FGFR1 gene amplification status by fluorescence in situ hybridization. In our study, 130 patients with lung SCC were included. Demographic information of the patients, tumor stage, lymph node involvement (N) and metastasis (M) status at the time of diagnosis, differentiation, last seen dates, death date of the patients were recorded. A total of 123 patients with adequate tumor cells were evaluated for FISH evaluation. FGFR1 amplification by FISH and immunohistochemical FGFR1 expression of the patients were examined. FISH-based amplification of FGFR1 has been defined as 25.2 % in patients with lung SCC. In this study, it was found that FGFR1 amplification was more common in early stage and non-metastatic patients in diagnosis and the overall survival rate was higher in the amplification cases. No relationship was found with the amount of smoking, differentiation, lymph node metastasis, age, gender, and tumor diameter. The high expression of FGFR1 was found to correlate with FGFR1 amplification. In addition, in three patients with basoidal type SCC, FGFR1 expression severity and percentage are higher and in two of these patients have FGFR1 amplification. A number of FGFR inhibitors are currently being analyzed in clinical trials. Our data suggest that FGFR1 can be not only a predictive or prognostic marker, but also a target for tumor therapy. The combined analysis of FISH and IHC expression of FGFR1 can help to identify criteria for selecting patients who can benefit from these new treatment options. Key Words: FGFR1, squamous cell lung carcinoma, amplification