The Prognostic Significance of Notch1 and Fatty Acid Binding Protein 7 (FABP7) Expression in Resected Tracheobronchial Adenoid Cystic Carcinoma: A Multicenter Retrospective Study

PURPOSE: Adenoid cystic carcinoma (ACC) of the trachea and bronchus is a rare tumor. Although MYB-NFIB oncogene fusion and Notch1 mutation have been identified in ACC, little is known about the expression and clinical significance of Notch1 and its target gene fatty acid binding protein 7 (FABP7) in tracheobronchial ACC. MATERIALS AND METHODS: Primary tracheobronchial ACC that were resected between 1998 and 2014 were identified through the pathology and oncology database from five thoracic oncology centers in China. A tissue array was constructed from the patients’ samples and the expressions of Notch1 and FABP7 were evaluated by immunohistochemistry. The association between the expression of both markers and survival was determined. RESULTS: Overexpression of Notch1 and FABP7, detected in 37.8% and 38.3% of 368 patients with tracheobronchial ACC, respectively, was an independent prognostic indicator for recurrencefree survival (RFS) by multivariable Cox proportional hazard model (p=0.032 and p=0.048, respectively). Overexpression of Notch1, but not of FABP7, predicted overall survival (OS) (p=0.018). When categorized into four groups according to coexpression of Notch1 and FABP7, patients with overexpression of both Notch1 and FABP7 belonged to the group with the shortest RFS and OS (p=0.01 and p=0.048, respectively). CONCLUSION: Expression of Notch1 and FABP7, and coexpression of Notch1 and FABP7, is strongly associated with poor survival in resected tracheobronchial ACC. These data are consistent with the hypothesis that poor differentiation of tracheobronchial ACC correlates with the activation of Notch signaling.