Background and Aims: The expression of NIMA-related kinase 2 (NEK2) is increased in a variety of malignant tumors, and is closely associated with tumor progression and patients’ unfavorable prognosis. However, the expression of NEK2 and its significance in pancreatic cancer are still unclear. Therefore, this study was conducted to investigate the NEK2 expression in pancreatic cancer tissue and its relationship with clinicopathologic factors and prognosis of the patients.  
Methods: The surgical specimens from 108 patients with pancreatic cancer undergoing pancreatectomy from January 2013 to December 2014 in the Department of Hepatopancreatobiliary Surgery of Hainan Provincial People's Hospital as well as the clinicopathologic and follow-up data of these patients were collected. The expressions of NEK2 in the tissue samples were detected by immunohistochemical staining. The relations of NEK2 with the clinicopathologic factors were analyzed, and the difference in tumor-free survival and overall survival rates between patients with different NEK2 expression levels were analyzed and compared by Kaplan-Meier survival curve and Log-rank analysis. The prognostic factors were determined by Cox proportional hazard model.
Results: There was no NEK2 expression in the normal pancreatic tissue, while in the 108 samples of pancreatic cancer tissue, high and low NEK2 expressions were found in 63 cases (58.3%) and 45 cases (41.7%), respectively. The NEK2 expression was significantly associated with CA19-9 level (P=0.015), TNM stage (P=0.002), tumor differentiation (P=0.034), and lymph node metastasis (P=0.043), but irrelevant to sex, age, smoking, CEA level, tumor size and tumor location (all P>0.05). The 1-, 3- and 5-year disease-free survival rates were 60.5%, 20.7% and 5.2% in patients with high NEK2 expression, and 75.4%, 50.6% and 24.9% in patients with low NEK2 expression, and the 1-, 3- and 5-year overall survival rates were 75.6%, 42.2% and 15.3% in patients with NEK2 expression, and 85.7%, 60.6% and 30.1% in patients with low NEK2 expression, respectively. Both disease-free survival and overall survival rates in patients with high NEK2 expression were significantly lower than those in patients with low NEK2 expression (both P<0.05). Univariate and multivariate analysis showed that TNM stage (P=0.029), lymph node metastasis (P=0.016) and NEK2 high expression (P=0.032) were independent influencing factors for tumor-free survival, and TNM stage (P=0.035), degree of differentiation (P=0.042), lymph node metastasis (P=0.006) and NEK2 high expression (P=0.000) were independent influencing factors for overall survival. 
Conclusion: High NEK2 expression is an independent risk factor for the prognosis of pancreatic carcinoma patients, and NEK2 can be used as an indicator for prognosis of pancreatic carcinoma patients after operation.