Endoscopic Ultrasound-Guided Locoregional Treatments for Pancreatic Neuroendocrine Neoplasms

Abstract

Pancreatic neuroendocrine neoplasms (pNENs) represent approximately 2% of all solid pancreatic tumors. The incidence of pNENs has been increasing in the last decade. The clinical manifestations of pNENs range from hormone secretion syndromes in functioning neoplasms (F-pNENs) to local infiltration or distant metastases in late-stage diagnoses or incidental findings in small non-functioning neoplasms (NF-pNENs). While surgery is the gold-standard treatment for larger and more aggressive tumors, small and low-grade tumors (G1) may be followed-up due to the indolent course of disease. Recently, endoscopic ultrasound (EUS)-guided ablative techniques, such as ethanol injection (EUS-EI) and radiofrequency ablation (EUS-RFA), have emerged as promising options for loco-regional ablations in selected cases. Despite promising safety profile and efficacy, high-quality evidence is needed to support their widespread adoption. This article reviews the current state of EUS-guided locoregional therapies, patient selection criteria, procedural details, and associated risks.

Keywords: EUS-RFA; NENs; NET; ablation; ethanol; insulinoma; neuroendocrine neoplasms; neuroendocrine tumors; radiofrequency.

Figure 1

(a) Endoscopic ultrasound image of a small hypoechoic insulinoma (functioning pancreatic neuroendocrine neoplasm) of the pancreatic neck; (b) contrast-enhanced harmonic endoscopic ultrasound (CH-EUS) after the injection of an ultrasound contrast agent showing a homogeneously hyper-enhanced neoplasm during the arterial phase, with a peripheral rim; (c) the 7 mm endoscopic ultrasound radiofrequency ablation probe (EUSRA, Taewoong Medical) insertion; (d) accurate tip control under endoscopic ultrasound evaluation; (e) EUS-RFA application at 40 Watt power setting, confirmed by the appearance of hyperechoic bubbles suggesting coagulative necrosis; (f) contrast-enhanced harmonic endoscopic ultrasound (CH-EUS) after the injection of an ultrasound contrast agent showing complete ablation with no residual vital tissue.

Figure 1

(a) Endoscopic ultrasound image of a small hypoechoic insulinoma (functioning pancreatic neuroendocrine neoplasm) of the pancreatic neck; (b) contrast-enhanced harmonic endoscopic ultrasound (CH-EUS) after the injection of an ultrasound contrast agent showing a homogeneously hyper-enhanced neoplasm during the arterial phase, with a peripheral rim; (c) the 7 mm endoscopic ultrasound radiofrequency ablation probe (EUSRA, Taewoong Medical) insertion; (d) accurate tip control under endoscopic ultrasound evaluation; (e) EUS-RFA application at 40 Watt power setting, confirmed by the appearance of hyperechoic bubbles suggesting coagulative necrosis; (f) contrast-enhanced harmonic endoscopic ultrasound (CH-EUS) after the injection of an ultrasound contrast agent showing complete ablation with no residual vital tissue.