High vimentin expression with E-cadherin expression loss predicts a poor prognosis after resection of grade 1 and 2 pancreatic neuroendocrine tumors

BACKGROUND: Pancreatic neuroendocrine tumors (pNETs) are a heterogeneous group of neoplasms with malignant behaviors that can develop from inert slow growth or low malignancy to aggressive metastasis during follow-up. Recently, vimentin and E-cadherin were shown to be prognostic markers in some malignant tumors but were not evaluated in pNETs. The aim of this study was to evaluate the expression and prognostic significance of vimentin and E-cadherin in grade 1 and 2 pNETs. METHODS: A retrospective review of 227 patients with grade 1 and 2 pNETs undergoing surgical resection was conducted. Tumor specimens were immunohistochemically stained for vimentin and E-cadherin. Correlations between vimentin and E-cadherin expression and other clinicopathological features were then analyzed. Furthermore, overall survival (OS) and disease-free survival (DFS) were evaluated using Kaplan-Meier and univariate and multivariate Cox regression methods. RESULTS: Among 227 patients, 55 (24.2%) harbored tumors with high vimentin expression, while 117 (51.5%) harbored tumors with loss of E-cadherin expression. Patients with high vimentin expression and loss of E-cadherin expression had significantly elevated risks of lymph node metastasis, distant metastasis, perineural invasion and an advanced American Joint Committee on Cancer (AJCC) stage compared with those with low vimentin expression and preserved E-cadherin expression, high vimentin expression and preserved E-cadherin expression, or low vimentin expression and loss of E-cadherin expression. Furthermore, multivariate analysis showed that high vimentin expression with loss of E-cadherin expression was an independent predictor of OS and DFS in patients with grade 1 and 2 pNETs who underwent resection (both P < 0.001). CONCLUSIONS: The current study demonstrated that high vimentin expression with loss of E-cadherin expression was correlated with lymph node metastasis, distant metastasis, disease progression and a poor prognosis in patients with grade 1 and 2 pNETs who underwent resection.