Page 11 - Read Online

Page 4 of 8 Cho et al. Mini-invasive Surg 2021;5:20 https://dx.doi.org/10.20517/2574-1225.2021.11

[Figure 3].

DISCUSSION
Outcomes of EUS-RFA in benign solid pancreatic tumor
Since Goldberg et al. first reported EUS-RFA for the pancreas in a porcine model in 1999, several studies
[12]
have demonstrated its effectiveness for various pancreatic tumors. Table 1 summarizes the clinical outcomes
of previous research.

[7]
In a study by Lakhtakia et al. , EUS-RFA was performed in three patients with symptomatic pancreatic
insulinoma using an internally cooled prototype needle electrode (EUSRA, STARmed). After ablation of
pancreatic insulinoma, symptomatic relief with biochemical improvement was achieved in all patients, and
[5]
patients were followed-up without symptoms for 12 months. In a prospective study by Choi et al. , 10
patients with benign solid pancreatic tumors [nonfunctional neuroendocrine tumor (NET), n = 7; solid
pseudopapillary neoplasm, n = 2; and insulinoma, n = 1] underwent EUS-RFA. After 16 EUS-RFA sessions,
a radiologic complete response was identified in seven patients during a median follow-up of 13 months
[Figure 4].

In a study by Barthet et al. , 12 patients with 14 NET underwent EUS-RFA. At the 1-year follow-up, 12
[13]
[14]
NETs showed complete response or lesion necrosis (86%). Oleinikov et al. performed ablation on 18
patients (NET, n = 11; and insulinoma, n = 7) with 27 lesions. All patients with insulinoma demonstrated
complete relief of hypoglycemia-associated symptoms and normalization of glucose levels was observed 1 h
after RFA. Radiologic complete response was achieved in 96.3% of patients (17 of 18) during a median of 8.7
months without clinically significant recurrence. In 2020, de Nucci et al. reported a prospective study on
[15]
EUS-RFA in 10 patients with 11 NETs. At the 12-month follow-up, all lesions demonstrated complete
disappearance with radiological normalization. A systemic review of published research on EUS-RFA for
NETs, including 12 studies and 61 patients with 73 tumors, showed an overall effectiveness rate of 96%
(75%-100%) in a mean follow-up period of 11 months (1-34 months) and an adverse event rate of 13.7%,
with no serious adverse events . In this review, a larger tumor was related with treatment failure (mean
[16]
size in the non-response group was 21.8 ± 4.71 mm vs. a mean size of 15.07 ± 7.34 mm in the response
group, P = 0.048). According to the ROC curve, a NET of size ≤ 18 mm at EUS was associated with a
positive response to EUS-RFA, with a sensitivity of 80% (95%CI: 28.4%-99.5%), a specificity of 78.6%
(95%CI: 63.2%-89.7%), and an AUC of 0.81 (95%CI: 0.67-0.95). EUS-RFA is an effective and safe treatment
for benign pancreatic tumors. However, the long-term outcomes are not well described. As solid pancreatic
tumors are slow to grow and have the potential of malignant transformation, long-term follow-up data are
mandatory to evaluate the outcomes of EUS-RFA.

Currently, EUS-guided ethanol ablation is most commonly used for treating pancreas cystic lesions.
Although the application of EUS-guided ethanol ablation for solid pancreatic tumors is limited, few reports
have demonstrated that EUS-guided ethanol ablation is effective and safe for treating benign solid
pancreatic tumors. In a study by Paik et al. , 8 patients with borderline malignant pancreatic tumors
[17]
underwent EUS-guided ethanol ablation (insulinoma, n = 3; nonfunctioning NET, n = 2; solid
pseudopapillary neoplasm, n = 2; and insulinoma, n = 1). After ethanol ablation, 6 patients (75%) achieved
treatment success. However, 2 patients still had persistent tumors. One patient experienced severe
pancreatitis after ablation. Among 6 patients who achieved initial treatment success, 1 patient experienced
tumor recurrence within 15 months. In a recent prospective study by Choi et al. , 33 patients who had 40
[18]
pathologically confirmed pancreatic NET (< 2 cm in diameter) underwent 63 sessions of EUS-guided
ethanol-lipiodol ablation. Complete ablation was achieved in 24 of 40 tumors (60%), with 1 (18 tumors,