EUS-Guided Biopsy Changes Management in Small Nonfunctioning Pancreatic Neuroendocrine Tumours: Endoscopy | August 2026

Introduction:

Active surveillance is increasingly considered for small (≤20 mm), low-risk nonfunctioning pancreatic neuroendocrine tumors (NF-PanNETs), but the need for routine tissue acquisition remains debated. This study evaluated whether EUS-guided fine-needle biopsy (EUS-FNB) provides clinically meaningful information that changes management, particularly according to tumor size.

Why was this study needed?

Many small NF-PanNETs can potentially be safely monitored rather than resected.

Imaging alone may not reliably define tumor biology and grade.

Pancreatic surgery carries substantial morbidity.

The benefit of routine EUS-FNB, particularly for lesions ≤10 mm, remains uncertain.

Results:

Among 417 lesions, EUS-FNB changed management in 16%, with greater impact in 11–20 mm tumors than in lesions ≤10 mm.

Biopsy findings led to surgical resection substantially more often in 11–20 mm lesions, making tumor size an important determinant of biopsy utility.

Tissue adequacy was excellent, and Ki-67 assessment was feasible in 96% of confirmed PanNETs.

EUS-FNB was generally safe, although concordance between biopsy and surgical tumor grade was not perfect.

Clinical Impact:

EUS-FNB appears particularly valuable for 11–20 mm NF-PanNETs, where tissue diagnosis and Ki-67 assessment can meaningfully shift management from surveillance to surgery. For very small lesions ≤10 mm, the clinical impact is considerably lower, supporting a more selective approach based on imaging characteristics, patient preference, and multidisciplinary assessment.

Bottom Line:

EUS-FNB provides meaningful management-changing information in small 11–20 mm NF-PanNETs and should be strongly considered before committing to surveillance. For lesions ≤10 mm, routine biopsy offers less benefit and should be individualized through shared decision-making.