Outcomes after endoscopic ultrasound-guided ethanol-lipiodol ablation of small pancreatic neuroendocrine tumors

Abstract

Background and aim: Little is known about the standard care of small (<2 cm in diameter) pancreatic neuroendocrine tumors (PNET). The aim of the present study was to determine the clinical outcomes of small PNET after endoscopic ultrasound (EUS)-guided ethanol-lipiodol ablation (EUS-ELA).

Methods: In this prospective cohort study, consecutive patients who underwent EUS-ELA for PNET were enrolled and were followed for ≥3 years. Treatment efficacy was the primary outcome measure.

Results: In total, 33 patients who had 40 pathologically confirmed PNET (<2 cm in diameter) were enrolled for final analysis. A total of 63 EUS-ELA sessions were successfully carried out (mean, 1.9 sessions per patient, 1.6 sessions per tumor), which included 40 initial sessions and 23 repeated sessions owing to incomplete ablation. Median actual volume of ethanol-lipiodol mixture injected per session was 1.1 mL (IQR 0.8-1.9 mL). Complete ablation was achieved in 24 of 40 tumors (60%) with one (18 tumors, 45%) or two (24 tumors, 60%) sessions of EUS-ELA. Lipiodol retention within tumor had better treatment outcomes (P = 0.004). Rate of procedure-related adverse events was 3.2%. No malignancy or lymph node metastasis was discovered during a median follow up of 42 months (IQR 39-46 months).

Conclusions: We found that EUS-ELA was a safe and effective alternative option in the management of PNET <2.0 cm in diameter; 60% of patients achieved complete ablation. Lipiodol retention within tumor may be a useful early predictor of treatment effectiveness. Trial registered at ClinicalTrials.gov (NCT 01902238).

Keywords: ablation; endoscopic ultrasound; ethanol; neuroendocrine tumor; pancreatic.