Prognosis based on the revised histological classification by the World Health Organization (2010) for pancreatic neuroendocrine tumors

Background/aim: Pancreatic neuroendocrine tumors (PNETs) are a rare subgroup of tumors, for which the factors predictive of survival and prognosis are not well known. Recently, the European Neuroendocrine Tumors Society (ENETS) proposed the TNM staging and the World Health Organization (WHO) revised its histological classification in 2010. This study aimed to evaluate whether the ENETS staging and the revised WHO classification can predict survival after surgical resection of PNETs. Methods: Twenty consecutive curative resections for PNETs were performed at our institute from 1998 to 2012. The prognostic factors based on the revised WHO histological classification (2010) for survival were retrospectively evaluated using the Kaplan–Meier method. Results: The mean patient age was 60.3 10.9 years. Twelve patients (60%) were diagnosed with functioning tumors and 8 (40%) with nonfunctioning tumors. Surgical methods comprised pancreatoduodenectomy (n 1⁄4 3), distal pancreatectomy (n 1⁄4 5), enucleation (n 1⁄4 9), and central pancreatectomy (n 1⁄4 3). Hepatectomy was performed for 2 patients with synchronous liver metastasis. According to the ENETS staging, 14 (70%), 2 (10%), 2 (10%), and 2 (10%) had stage I, II, III, and IV tumors, respectively. According to the revised WHO histological classification (2010), 13 (65%), 5 (25%), 1 (5%), and 1 (5%) patient was diagnosed with neuroendocrine tumor (NET) G1, NET G2, neuroendocrine carcinoma (NEC), and mixed adenoneuroendocrine carcinoma (MANEC), respectively. Univariate analysis revealed that both the ENETS staging and the revised WHO histological classification (2010) significantly predicted survival after surgical resection for PNETs. Conclusions: The ENETS staging and the revised WHO histological classification (2010) may be useful to predict survival in PNETs. However, because PNETs represent a rare tumor subgroup, more time and a sufficient number of cases are required to confirm its prognostic reliability.