Evaluation of the treatment strategy for small non-functioning pancreatic neuroendocrine tumors G1: resection versus active surveillance at a retrospective single-center study

Surgical resection is the standard treatment for non-functioning pancreatic neuroendocrine neoplasms (NF-PanNENs). However, it is unclear whether resection or active surveillance is the recommended treatment for small- and low-grade NF-PanNENs. Therefore, in this study, we aimed to clarify the appropriate treatment strategy for these NF-PanNENs. We analyzed the data of 119 patients who were pathologically and clinically diagnosed with NF-PanNENs. We evaluated the associations between treatment methods and oncological outcomes, as well as the details of surgery-related complications and morphological changes during follow-up. A total of 74 patients had neuroendocrine tumor (NET) G1 with tumor diameter ≤ 20 mm. Of these, 23 (31%) and 51 (69%) patients underwent active surveillance and surgical resection, respectively. There were no significant differences in the 5-year disease-specific and overall survival rates between the two groups (P = not available and 0.78, respectively). In the active surveillance group, no cases of radiological evidence of lymph node or distant metastasis were detected during the observation period. Eight patients (35%) showed tumor growth, with a mean tumor growth diameter of 0.65 mm per year and a maximum increase in tumor size of 4 mm. In the surgical resection group, no recurrence was observed, and the rates of postoperative complications (Clavien–Dindo grade ≥ Ⅲ), new-onset diabetes mellitus, pancreatic enzyme intake, and readmission owing to surgery-related complications were 29%, 18%, 12%, and 14%, respectively. Considering both prognosis and surgery-related complications, active surveillance may be a tolerable treatment strategy for NF-PanNET G1 with a tumor diameter ≤ 20 mm.