E461: Validation of a Disease-Specific Survival Model for Resected Entero-Pancreatic Neuroendocrine Neoplasms

A multicenter European trial found recurrence-free survival for entero-pancreatic neuroendocrine tumors (NETs) was associated with grade, stage, and lymph node ratio (LNR). In this study, we validate this model for disease-specific survival (DSS).

Methods:

The Surveillance, Epidemiology, and End Results (SEER) database was accessed to identify patients with entero-pancreatic NETs between 2004-2017. Inclusion criteria included follow-up of at least 24 months, grade 1/2, surgical resection, and age < 85 years. LNR was defined as the number of positive nodes over the total resected nodes, with cut-off values based on prior literature (0.2 for pancreatic and 0.6 for small bowel NETs). The data was analyzed using R software.

Results:

A total of 8,745 patients met our inclusion criteria, 3,235 pancreatic and 5,510 small intestine NETs. Patients with small bowel NETs were older (p< 0.001), had more advanced stages (III and IV) (p< 0.001) and higher LNR (p< 0.001). Patients with pancreatic NETs were more likely to have stage I and II disease (p< 0.001) and be of “other” race (p< 0.001). Overall DSS was 95.1% at five years and 86.4% at ten years. On univariate and multivariate analysis, higher grade (p< 0.001), stage (p< 0.001), and LNR (p< 0.001) were associated with DSS. The primary site of disease (p=0.3) and sex (p=0.7) were not associated with DSS. Interestingly, regional nodal metastasis (stage III) compared to stage I/II was not associated with DSS (p=0.6 univariate, p=0.2 multivariate). However, stage IV disease was associated with lower DSS (p < 0.001).

Conclusions:

Like the previously reported recurrence-free survival model, grade and LNR were predictors of DSS. Although stage IV disease was associated with DSS, regional nodal metastasis was not.