Prognostic Factors and Management Approaches for Small Nonfunctional Pancreatic Neuroendocrine Tumors: Insights from SEER Data.

Objective: To explore the optimal management strategies for small-sized nonfunctional pancreatic neuroendocrine tumors (NF-PanNETs) and to assess the rationale for the 'wait and see' approach.

Methods: This retrospective study analyzed data from 2,052 patients with small-sized NF-PanNETs (tumor size ≤20 mm) diagnosed between 2004 and 2019. Patients were further divided into two groups: those with tumors ≤10 mm (n = 573) and those with tumors 11-20 mm (n = 1,479). Demographic information, clinical characteristics, and survival outcomes were obtained and compared using the Surveillance, Epidemiology, and End Results (SEER) database.

Results: Tumors ≤10 mm were less likely to exhibit adjacent structure invasion (p = 0.005), lymph node involvement (p = 0.028), or distant metastasis (p < 0.001). Among T1N0M0 patients, both surgery and surveillance yielded similar cancer-specific survival (CSS) for those with tumors ≤10 mm, while surgery was significantly associated with better CSS for patients with tumors in the 11-20 mm range (p = 0.040). Multivariate analyses identified age >65 years, poor differentiation, T4 stage, and M1 stage as independent predictive factors for worse outcomes (all p < 0.001).

Conclusions: Compared to NF-PanNETs ≤10 mm, tumors sized between 11 and 20 mm are associated with higher risks of adjacent structure invasion, lymph node involvement, and distant metastasis. Tumors ≤10 mm can be safely monitored with active surveillance.