Survivals of patients with surgically treated and High-grade pancreatic neuroendocrine carcinomas: A comparative study between two American Joint Committee on Cancer 8th tumor-node-metastasis staging systems

Background and objectiveWe aimed to compare the two new defined tumor-node-metastasis (TNM) systems in the American Joint Committee on Cancer (AJCC) 8th staging manual for overall survival (OS) analysis of G3 pancreatic neuroendocrine carcinomas (p-NECs) that are currently proposed for pancreatic exocrine adenocarcinomas (p-EACs) and G1/G2 pancreatic neuroendocrine tumors (p-NETs), respectively.MethodsThe data of patients who were surgically treated and histopathologically diagnosed with G3 p-NECs at West China Hospital of Sichuan University from January 2002 to June 2017 were retrospectively analyzed and compared using the two new AJCC staging systems.ResultsApplying the p-EAC AJCC 8th TNM staging system to G3 p-NECs, the estimated 3-year OSs for each stage were 86.7%, 76.0%, 44.5% and 20.7%, respectively (P < 0.001). According to the G1/G2 p-NETs staging system, the estimated OSs at 3 years for each new AJCC stage were 100.0%, 83.6%, 47.1% and 20.7%, respectively (P < 0.001). The system for p-EACs significantly discriminated the survival difference of G3 p-NECs between Stage I and Stage II (P = 0.019), while the other one for G1/G2 p-NETs could not (P = 0.108). The consistent results of Akaike information criteria with Harrell's concordance index indicated that the AJCC 8th staging system for p-EACs was superior when applied to G3 p-NECs for its better prognostic stratification and more accurate prediction ability for OS.ConclusionsOur analysis demonstrated that both TNM systems in the AJCC 8th staging manual were prognostic for patients with G3 p-NECs; however, the classification originally applied to p-EACs was superior and supported its use in clinical practice.