Functional and non-functional pancreatic neuroendocrine tumours: ENETS or AJCC TNM staging system?

There are currently 2 Tumour-Node-Metastasis (TNM) staging systems for pancreatic neuroendocrine tumours (p-NETs) - European Neuroendocrine Tumour Society (ENETS) and American Joint Committee on Cancer (AJCC). P-NETs being heterogeneous, we investigated the prognostic value of the 2 systems in p-NETs, as a whole, and more interestingly in functional and non-functional sub-groups separately, with a view to ascertaining any potential clinical benefits of using one system over the other.

Data from patients with surgically resected p-NETs were retrospectively reviewed. Kaplan-Meier method and Cox Regression proportional hazards model were used to analyse overall survival (OS) and prognostic predictors respectively.

In the whole group of 165 patients, both TNM systems successfully discriminated OS differences when comparing stages I and II with stages III and IV (P<0.05); ENETS stage III patients had a significantly better OS than those in stage IV (P=0.003). Patients with functional p-NETs in ENETS stage II showed a statistically better OS than those in stages III and IV (P<0.05). For non-functional tumours, the AJCC staging system could effectively discriminate between the OS differences of patients in stage I with stages III and IV, or stage II with III and IV (P<0.05). Along with surgical intent and World Health Organisation (WHO) 2010 grade, both ENETS and AJCC staging systems were effective predictors of OS for different function-status p-NETs.

The ENETS system might have potential advantages when applied to all p-NETs and to the functional sub-group, while the AJCC system might be clinically more practical for non-functional p-NETs.