High Expression of FGF5 Is an Independent Prognostic Factor for Poor Overall Survival and Relapse-Free Survival in Lung Adenocarcinoma.

Lung cancer is not only a serious disease but also a public problem threatening human health all over the world. Nonsmall cell lung cancer-which accounts for the majority of lung cancer-is mainly composed of lung adenocarcinoma (LUAD) and squamous cell carcinoma (LUSC). FGF5 is a gene located in q21.21. In the past years, research on FGF5 is mainly focused on hair length and hereditary spherocytosis. In our study, bioinformatics analysis of FGF5 was performed through multiple databases. Expression of FGF5 was compared between tumor and normal tissues, association between gene expression and clinical outcomes was investigated in LUAD and LUSC separately, and potential signaling pathways were predicted. FGF5 expression was upregulated in lung cancer tissues compared with normal tissues. What is more, the high FGF5 expression group had significantly lower proportions of lymph node negative (N0) patients (77/144, 53.5%, vs. 253/358, 70.7%, p = 0.000), and is associated with worse overall survival (OS) (p < 0.0001) and relapse-free survival (RFS) (p = 0.024) in LUAD patients, which could not be seen in LUSC. The following analysis confirmed that high FGF5 expression could be an independent prognostic factor for poor OS (HR: 0.431, 95% CI: 0.312-0.597, p = 0.001) and RFS (HR: 0.678, 95% CI: 0.471-0.977, p = 0.037) in LUAD, but not in LUSC. Coexpression genes related to FGF5 were explored and potential pathways were investigated for further research. FGF5 is a tumor-associated gene that upregulated in lung cancer tissues, and could be an independent prognostic factor that have potential value for further research.