Page 73 - Read Online

Suwa et al. Mini-invasive Surg 2022;6:20 https://dx.doi.org/10.20517/2574-1225.2021.123 Page 5 of 11

The advantages of CSP include a simple procedure, a short procedure time, and a low complication rate
(bleeding and perforation). On the other hand, the disadvantages of CSP are the limited indications for
small lesions and noncancerous lesions and a low R0 resection rate, which are common to lesions in both
the colon and the duodenum.

CSP for SNADETs (other report)
[12]
Regarding the CSP for SNADETs, only one report from a single center is available. Okimoto et al.
reported a good long-term outcome of CSP for the treatment of sporadic SNADETs. In this report, 35
patients with SNADETs and 46 lesions were evaluated. The median lesion size was 4 mm (range, 2-7 mm); 2
lesions were located in the duodenal bulb, 40 were in the 2nd portion, and 4 were in the 3rd portion.
Overall, 11 tumors were the macroscopic type 0-I in the Paris classification, 21 were 0-IIa, 12 were 0-IIa+IIc,
and 2 were 0-IIc. The en bloc resection rate was 97.8%, and histopathological evaluations showed that there
were 37 adenomas and 9 nontumor lesions. For the adenomatous lesions, the R0 resection rate was 70.3%
(26/37), and only one lesion (2.7%) in the 36 lesions had recurrence during a median follow-up period of 48
months (3-64 months).

[12]
Comparing the short- and long-term outcomes between those of Okimoto et al. and our institution
[Table 2], both showed that CSP had a high rate of en bloc resection and a high rate for the completion of
the procedure, with excellent long-term results, despite the low R0 resection rate, and no intra- and
postoperative adverse events were observed. However, it should be noted that, although very rare, spurting
[14]
[13]
delayed bleeding and severe acute pancreatitis as serious adverse event might occur after duodenal CSP.
With the above results, we believe that CSP for SNADETs should be considered for adenomatous lesions
that are sized 10 mm or less. A multicenter prospective study with further long-term follow-up is currently
ongoing, and the results will confirm the efficacy and safety of CSP.

UNDERWATER ENDOSCOPIC MUCOSAL RESECTION
Binmoeller et al. first reported UEMR for colorectal polyps in 2012. Technically, the lesion is lifted and
[15]
floated away from the muscularis propria by air deflation and water immersion; then, strangulation with
mucosal and submucosal tissue is easily performed, even for flat or sessile lesions.

UEMR for colorectal polyps
A multicenter RCT previously reported that UEMR significantly improved the R0 resection and en bloc
[16]
resection rates compared to conventional EMR (cEMR) for colorectal polyps 10-20 mm in size [69% (59-
77%) vs. 50% (40-60%), P = 0.01; 89% (81-94%) vs. 75% (65-83%), P = 0.007]. This study also showed that
UEMR did not increase the incidence of adverse events. In another report , the local recurrence rate at the
[17]
first follow-up colonoscopy was lower in tumors that were treated with UEMR than in the tumors that were
treated with cEMR (7.3% vs. 28.3%, P = 0.008). A prospective RCT comparing UEMR and cEMR in 20-40
[18]
mm sessile or flat colorectal polyps showed that the en bloc and R0 resection rates were 33.3% vs. 18.4% (P =
0.045) and 32.1% vs. 15.8% (P = 0.025), respectively. The results show statistical significance for the
advantages of UEMR over cEMR, but both treatment outcomes were unsatisfactory. Therefore, no positive
evidence is available to indicate UEMR for lesions larger than 20 mm.

There is no specific indication for UEMR in any of the guidelines of any country. To summarize the above
reports, because few reports have suggested the usefulness of UEMR for lesions larger than 20 mm, the
definite indication might be for lesions that are 20 mm or less. In addition, UEMR may also be effective for
recurrent lesions with severe fibrosis in the submucosa .
[19]