Expression levels of HER2 and MRP1 are not prognostic factors of long-term survival in 829 patients with esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is the eighth most frequent neoplasm in China. However, the expression levels of human epidermal growth factor receptor 2 (HER2) and multidrug resistance protein 1 (MRP1) in patients with ESCC remain to be determined. In the present study, 829 ESCC cases were evaluated using immunohistochemistry. The association between the expression levels of HER2 and MRP1 and the patient's clinicopathological factors was analyzed using Fisher's exact test or χ2 test. Univariate analysis was performed via Kaplan-Meier survival curves, while the Cox proportional hazard model was used for multivariate analysis. A significant correlation was observed between the expression levels of HER2 and the patient's gender (P<0.050), tumor size (P=0.013) and venous/lymphatic invasion (P=0.039). However, no significant correlation was identified between the expression levels of MRP1 and the clinicopathological factors of the patients. In univariate analysis, gender, differentiation, depth of invasion, clinical stage, adjuvant radiotherapy or chemotherapy and lymph node metastasis were significantly correlated with progression-free survival (PFS) and overall survival (OS) in patients with ESCC (P<0.050). The graphical representation of the Kaplan-Meier estimate curves suggested that the expression levels of HER2 or MRP1 did not exert any influence on prognosis (log-rank test, P>0.050). In multivariate analysis, tumor location, gender, clinical stage, differentiation and lymph node metastasis were identified as independent factors of prognosis in patients with ESCC (P<0.050). However, the expression levels of HER2 or MRP1 were not independently associated with PFS or OS in these patients. In conclusion, the present large-scale study demonstrates that the protein expression levels of HER2 and MRP1 does not exert any influence on the prognosis of ESCC.