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Page 2 of 8 Kato et al. Mini-invasive Surg 2022;6:10 https://dx.doi.org/10.20517/2574-1225.2021.124

[5-8]
mortality of PD range 30%-40% and 1%-4%, respectively . This high morbidity makes PD too invasive for
[9]
SNADETs, which has a relatively low risk of lymph node metastasis . Endoscopic submucosal dissection
(ESD) is the standard treatment for neoplasms in gastrointestinal tract because of its lower invasiveness.
However, duodenal ESD is very different from that of other organs in terms of the technical aspects of the
procedure and post-ESD management. In this narrative review, we focus on the current status and issues of
duodenal ESD.

INDICATIONS FOR ESD AND CURE CRITERIA
To date, there is no established consensus on the indications for duodenal ESD. The malignant potential of
the lesion is important in determining the indication for endoscopic treatment. Nakayama et al. reported
[10]
that the proportion of lesions diagnosed as category 4 (equivalent to high-grade dysplasia) or higher of the
Vienna classification after ER of SNADETs was 6% for lesions less than 7 mm, but it gradually increased
with the size of the lesion, reaching 52% for lesions 16 mm or larger. It is important to consider the
resectability of each treatment method and the risk of adverse events when considering the indications for
treatment. ESD is reported to accomplish secure en bloc resection for superficial epithelial tumors arising
from the gastrointestinal tract irrespective of the size and location [11-14] . Similarly, duodenal ESD
accomplishes higher en bloc resection rates in previous reports [15-22] . Moreover, a recent multicenter
retrospective study including more than 3000 cases undergoing duodenal endoscopic treatment in Japan
reported high duodenal ESD en bloc resection rates regardless of the size, location, or presence of fibrosis of
the lesion, whereas other endoscopic resection techniques including endocopic mucosal resection (EMR)
and underwater EMR revealed inferior resectability, especially for lesions larger than 20 mm . In terms of
[23]
the adverse events, the delayed AE rate of ESD was significantly higher than that of the non-ESD treatments
for lesions less than 19 mm (ESD 7.4% vs. others 1.9%, P < 0.0001); however, this difference disappeared in
lesions larger than 20 mm (ESD 6.1% vs. others 7.1%, P = 0.6432). Based on these results, it seems reasonable
to consider 20 mm or larger lesions as an indication for ESD at this time, although ESD should be
performed by highly experienced endoscopists considering its high adverse event rate. As for occupied
circumference, as described below, even large mucosal defects can be healed without causing stricture by
complete suturing along the long axis of the intestine, so that even circumferential lesions can be treated
endoscopically as long as complete suturing can be obtained. However, duodenal ESD is still technically
extremely challenging, therefore piecemeal resection is still an option in institutions where en bloc resection
by ESD is difficult.

Regarding curative criteria, the risk of metastasis is important, since ESD is only a local resection.
Information regarding curability of duodenal ESD is still insufficient due to its rarity. There is no
established concept of “early duodenal cancer”, whereas generally “early cancer” is defined as cancer with
invasion limited to mucosa or submucosa in the stomach and colorectum. Regarding lymph node
metastasis (LNM), intra-mucosal cancer indicates no incidence of LNM , and the LNM of submucosal
[24]
cancer is about 40% [24-26] . Based on these facts, intra-mucosal cancer can be cured by ESD alone, while
submucosal cancer cases should be referred to additional surgery with lymph node dissection.

KNIFE
As described below, duodenal ESD is technically extremely difficult; the most careful technique is required.
especially during submucosal dissection. For this reason, a needle-shaped energy device is preferable. which
enables fine dissection. Indeed, we reported that a needle type with a water irrigation function significantly
shortens the procedure time for duodenal ESD . Furthermore, recently, a scissor-type knife has also been
[27]
[28]
reported to be safe and secure duodenal ESD .