Background: The role of routine endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) of small (≤20 mm) nonfunctioning pancreatic neuroendocrine tumors (NF-PanNETs) remains debated. We evaluated the impact of EUS-FNB on clinical management of very small (≤10 mm) and small (11-20 mm) suspected NF-PanNETs in patients who were otherwise suitable for active surveillance.
Methods: This was a retrospective analysis of patients with single, sporadic, ≤20-mm lesions, exhibiting typical imaging features of NF-PanNET, who were referred for EUS-FNB at two high-volume centers (January 2017-December 2024). The primary outcome was impact of EUS-FNB on management (a diagnosis leading to a strategy other than active surveillance). Secondary outcomes included factors associated with substantial management change, sample adequacy, safety, Ki-67 assessment, and concordance between EUS-FNB and surgical grading.
Results: 417 lesions (160 [very small]; 257 [small]) were included. EUS-FNB changed management in 68 cases (16.3%), more frequently in small lesions (19.8% vs. 10.6%; P = 0.01). A substantial impact leading to surgical resection was more frequent in small lesions (12.4% vs. 3.7%; P = 0.002). Lesion size 11-20 mm was independently associated with substantial impact (odds ratio 3.19, 95%CI 1.05-9.66). Sample adequacy was 96.1%, adverse event rate was 3.4%, Ki-67 was feasible in 96.0% of confirmed PanNETs, and grading concordance with surgical specimens was 78.1%.
Conclusions: In patients with suspected small NF-PanNET without suspicious features, EUS-FNB provided a clear clinical benefit for larger lesions (11-20 mm). For very small lesions (≤10 mm), its more limited impact supports individualized, shared decision making with the patient.
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