Prognostic significance of cytokeratin 19 expression in pancreatic neuroendocrine tumor: A meta-analysis

BACKGROUND Pancreatic neuroendocrine tumor (PNET) comprises 1-2% of all pancreatic tumors, but its incidence is increasing. Although many studies have investigated the correlation between cytokeratin 19 (CK-19) and PNET, the prognostic significance of CK-19 expression in PNET is inconclusive. METHODS Eligible studies were retrieved from Pubmed, Elsevier, Embase, Cochrane Library and Web of Science databases. All relevant data were extracted to analyze the relationship between CK-19 and PNET. We utilized a fixed or random effects model to calculate the pooled odds ratio (OR) with 95% confidence intervals (CI). RESULTS Pooled data indicated CK-19 expression was significantly associated with poor 3- and 5-year overall survival (OS) for PNET, but not for 1-year overall survival. Additionally, positive CK-19 expression was correlated with large tumor size, advanced differentiation grade in World Health Organization-2010 (WHO-2010) and WHO-2004, vascular invasion, lymph node metastasis and liver metastasis. CONCLUSIONS Positive CK-19 expression can be used as a predictor of poor prognosis of PNET.