Background and aims: Endoscopic ultrasonography (EUS)-guided ethanol injection (EI) has recently been introduced as one of the management methods against pancreatic neuroendocrine neoplasms (PNENs). Here, we aimed to evaluate the efficacy and safety of EUS-guided EI against small PNENs by multicenter prospective study.
Methods: This study was conducted as a multicenter, single-arm, prospective phase II study in six high-volume medical centers in Japan between September 2020 and July 2023. The major eligibility criteria was the presence of a pathologically diagnosed grade 1 tumor within 15 mm in diameter. A composite primary endpoint consisting of efficacy and safety was set in this study. Efficacy was set as the achievement of complete ablation evaluated using contrast-enhanced CT at 1 and 6 months. Safety was set as avoiding severe adverse events within 1 month, severe pancreatic fistula at 1 month, and incidence and/or exacerbation of diabetes mellitus (DM) at 6 months after treatment. The composite endpoint achievement by EUS-EI compared with the results of the historical controls by surgical treatment.
Results: In total, 25 patients with PNENs were treated by EUS-EI. Notably, 76% of patients achieved the composite primary endpoint (19/25) (95% confidence interval (CI), 54.9-90.6), a significantly higher proportion compared with that by surgical treatment (p = 0.0083). For efficacy, 88% (22/25) achieved complete ablation at 1 and 6 months, respectively (95% CI, 68.8-97.5). Regarding safety, 96% of the patients (24/25) had no severe adverse events within 1 month (95% CI, 79.7-99.9%), no patients had severe pancreatic fistulas at 1 month, and 84% of the patients (21/25) had no incidence and/or exacerbation of DM at 6 months (95% CI, 63.9-95.5).
Conclusion: EUS-EI is could be a potent treatment option in patients with small PNENs.
Japan Registry of Clinical Trials (jRCT) registration ID: jRCTs061200016

Tatsuhiro Yamazaki

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