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Page 4 of 9 Ishihara. Mini-invasive Surg 2021;5:36 https://dx.doi.org/10.20517/2574-1225.2021.72

Table 1. Indications for endoscopic submucosal dissection

√ Clinical T1a-epithelial/lamina propria (EP/LPM) N0M0 non-circumferential lesion
√ Clinical T1a EP/LPM N0M0 circumferential lesion ≤ 50 mm
√ Clinical T1a MM/T1b SM1 cancer (invading submucosa by ≤ 200 µm) N0M0 non-circumferential lesion
T1a MM/T1b SM1: T1a-Muscularis Mucosae/T1b-Submucosa 1.

Previous reports [14-18] showed that 27.4%-55.2% of cancers diagnosed as (c)MM/SM1 before treatment were
(p)EP/LPM cancers [Figure 2], for which endoscopic resection is highly likely to be curative. This indicates
that the accuracy of preoperative diagnosis for (c)MM/SM1 cancers is poor, and that a considerable
proportion of esophageal SCC, which is curable by ESD, is included in (c)MM/SM1 cancers. Based on these
facts, (c)MM/SM1 cancers are considered as an indication for ESD.

Lateral extent of cancer
Although ESD is an effective treatment, extensive esophageal endoscopic resection can lead to postoperative
esophageal strictures, with rates of postoperative stricture after non-circumferential and whole
circumferential resection of 60.7%-75% and 100%, respectively, if preventive measures are not applied [19-21] .
Stricture after esophageal ESD causes dysphagia and requires multiple, long-term endoscopic balloon
dilatations. It thus has a negative impact on the patient’s quality of life and may delay additional
chemoradiotherapy after non-curative resection. However, the use of appropriate preventive measures can
reduce the proportion of strictures after non-circumferential resection to 11.3%-36.2% [19,20,22] . Non-
circumferential lesions are thus considered as an indication for ESD, whereas the risk of stricture following
circumferential resection remains high, despite preventive measures.

The application of stenosis-preventive measures following circumferential resection was associated with
stenosis rates of 76% in 45 patients who received steroid injection therapy [23-27] , 55% in 44 patients who
received oral steroid therapy [25,26,28-30] , and 71% in 14 patients who received both injected and oral steroid
[19]
therapy . However, these studies included widespread lesions with a mean major axis length of 6 cm. A
previous report showed that a resection diameter > 50 mm increased the stricture risk: when the major
[26]
resection axis length was > 50 mm, 85% of patients (11/13 patients) required at least six sessions of
dilatations, compared with only 17% of patients (1/6 patients) with a length ≤ 50 mm. Furthermore, the
administration of oral steroid prednisolone at a starting dose of 30 mg and tapered for 12-18 weeks limited
the stenosis rate to 27.3% (3/11 patients) in patients who underwent whole-circumferential resection,
[25]
requiring a mean of only 1.6 sessions of balloon dilatation . These reports confirm that stricture relief can
be achieved more easily in tumors with a major axis length ≤ 50 mm, and effective methods are being
developed to prevent stricture following whole-circumferential stenosis.

Expected curability is another important factor determining the indication for ESD. Although, no studies
have reported on the pathologic results for cEP/LPM cancer with circumferential extent, a previous report
showed that approximately 70% of cEP/LPM cancers ≥ 50 mm were (p)EP/LPM cancers . Conversely,
[31]
however, another study showed that only 14% (2/14 lesions) of (c)MM/SM1 whole-circumferential
[32]
cancers were (p)EP/LPM cancers. In addition, 86% (12/14 lesions) of (c)MM/SM1 whole-circumferential
cancers were at high risk of metastasis (submucosal cancer or vascular invasion positive) or had lymph node
metastasis. From the perspective of accuracy for preoperative diagnosis of cancer invasion depth, further
investigation is needed regarding the adequacy of ESD for (c)MM/SM1 whole-circumferential cancers.
Considering the expectancy of curability and postoperative complications, ESD is therefore recommended
for cT1a-EP/LPM superficial SCCs with a major axis length ≤ 50 mm and involving the entire circumference
of the esophagus, upon implementing preventive measures for stenosis.