Extranodal extension influences prognosis in pancreatic head cancer.

Abstract

593 Background: Extranodal extension (ENE) is an established prognostic factor of several gastrointestinal cancers; furthermore, ENE is already included as one component of nodal category of oral cavity, penis, and vulvar cancers. However, the prognostic impact of ENE in pancreatic cancer remains unclear. In this study, we aimed to investigate prognostic implication of ENE in patients with surgically resected pancreatic cancer. Methods: We retrospectively reviewed electronic medical records and pathologic slides of 503 surgically resected pancreatic head cancer patients, who consecutively underwent pancreaticoduodenectomy for pathologically confirmed pancreatic ductal adenocarcinoma between January 2009 and December 2013. Patients were categorized into subgroups according to ENE status and AJCC 8th pancreatic cancer staging system. We compared the disease-free survival rates of the patients according to ENE status. Cox proportional hazard analysis was performed to evaluate prognostic factors for the disease-free survival of pancreatic head cancer. Results: ENE-positive patient group showed a larger tumor size, a higher rate of lymph node metastasis, and a tendency to be positive for lymphovascular invasion, perineural invasion, and resection margin (p < 0.001). Patients with ENE had lower overall survival (OS) and disease-free survival (DFS) rates compared with those without ENE (N0, 30 months; LN+/ENE-, 20 months; LN+/ENE+, 16 months; p < 0.001), (N0, 13 months; LN+/ENE-, 8 months; LN+/ENE+, 5 months; p < 0.001). Patients with higher N categories had lower OS and DFS rates. In addition, even in the same N stage, patients with ENE showed lower OS and DFS rates than those without ENE (p < 0.001). However, there was no significant difference in survival rates between patients in the N1/ENE+ group and the N2/ENE- group. Additionally, ENE was an independent prognostic factor for pancreatic cancer. Conclusions: ENE significantly influenced adverse prognosis among patients with pancreatic head cancer especially for those with nodal metastasis. Therefore, ENE should be considered as a prognostic factor in the future editions of the AJCC staging system.