Prognostic implications of FGFR1 and MYC status in esophageal squamous cell carcinoma

AIM To investigate the clinicopathological features and prognostic implications of combined MYC and fibroblast growth factor receptor 1 (FGFR1) status in esophageal squamous cell carcinomas (ESCCs). METHODS All patients with ESCC (n = 180) underwent surgical resection at Seoul National University Hospital sometime between 2000 and 2013. A tissue microarray was constructed using cores obtained from representative tumor areas of formalin-fixed, paraffin-embedded tissue blocks. FGFR1 and MYC copy numbers were quantified using fluorescence in situ hybridization. The level of MYC expression was determined using immunohistochemistry. FGFR1 and MYC amplification status was compared between primary and metastatic lymph nodes. Univariate and multivariate survival analyses were performed according to adjuvant therapy status. RESULTS FGFR1 and MYC amplifications were observed in 21.4% (37/173) and 54.2% (91/168) of patients, respectively, while MYC expression was observed in 58.9% (106/180) of patients. There was a positive correlation between MYC amplification and overexpression (P = 0.002). Although FGFR1 amplification was not associated with MYC amplification or expression, 12.3% (20/163) of patients exhibited both FGFR1 amplification and MYC expression. There was also a correlation in FGFR1 amplification status between matched primary tumors and metastatic lymph nodes (P < 0.001). MYC expression was higher in ESCCs with pT1 (P < 0.001) and in those with no lymph node metastasis (P = 0.023). MYC expression was associated with prolonged disease-free survival (P = 0.036) and overall survival (OS) (P = 0.017) but was not an independent prognostic factor. FGFR1 amplification was an independent predictor for prolonged OS in all patients (P = 0.029) and in those who did not receive adjuvant therapy (P = 0.013). Combined FGFR1 amplification and MYC expression predicted better OS in patients who did not receive adjuvant therapy (P = 0.034) but not in those who did receive adjuvant therapy. CONCLUSION FGFR1 amplification and MYC expression have prognostic implications in resected ESCCs with respect to adjuvant therapy. The role of FGFR1-targeted therapy in ESCC remains to be explored.