Traction is most important for the widespread use of endoscopic submucosal dissection, especially in procedures presenting particular difficulty

We read the article from Su et al. [1] with great interest. The authors re-evaluated the safety and efficacy of traction-assisted endoscopic submucosal dissection (TA-ESD) relative to conventional ESD (C-ESD) in a study that was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. They performed subgroup analyses according to lesion location and meta-regression using lesion size.

Their results demonstrate once more the benefits of TA-ESD over C-ESD, namely its shorter procedure time and association with fewer complications, as well as a similar R0 resection rate.

The strengths of this meta-regression analysis, compared with the only previous similar study are, first its larger scale, including 11 randomized controlled trials (RCTs), and secondly, a more comprehensive evaluation using a risk of bias tool. Thirdly, each outcome was clarified by segmenting data for the esophagus, stomach, and colorectum, and fourthly, meta-regression was used to better understand the source of heterogeneity.

One of the present authors developed a sinker-traction device [2] for difficult colorectal ESD, and used the traction technique for several cases when his unit had just begun to introduce colonic ESD.

After his unit’s ESD technique had stabilized, he rarely used the sinker-traction approach for ESD, but gravity, waterjet traction, and gentle pressure to the dissected part of the lesion from the short-type transparent hood are always important for effective standard ESD.

In the West, after the second author of this article and his colleagues [3] first developed clip and band traction for gastric ESD [3], Jacques et al. [4] have also used a similar technique for large numbers of colorectal ESDs with excellent results.

The important considerations for ESD are safety, effectiveness, procedure time, and cost, and in our opinion, safety and effectiveness are the most important among these.

“For ESD experts, conventional ESD mostly provides similar results compared with traction-assisted (TA)-ESD … However, TA-ESD has an important role in difficult cases, such as gastric ESDs in the greater curvature, fibrotic esophageal ESDs, and cecal or proximal colon ESDs.”

Regarding safety in this meta-analysis [1] the subset analyses of the esophagus and colorectum yielded similar results, namely that TA-ESD had a lower complication rate than C-ESD, with statistical significance; that for the stomach showed a lower complication rate with TA-ESD with, however, only marginal significance.

In addition, perforation is the most important and severe complication related to ESD. In the subgroup analyses the perforation rate was lower in the esophageal TA-ESD subgroups compared to the C-ESD group but there was no significant difference for gastric and colorectal ESDs. These results seem reasonable, in our opinion, given the differences in the technical difficulty of ESD in the esophagus, stomach, and colorectum. In gastric ESD, the risk of perforation is lower because of the thicker muscle layer, and conventional endoscopic clipping is usually enough even when perforation has occurred. It is reasonable that there was no statistically significant difference in the perforation rate for gastric ESD.

The Japanese multicenter RCT comparing the two methods for gastric neoplasms (by the CONNECT-G Study Group) also showed no statistically significant difference in the primary end point of total procedure time for TA-ESD versus C-ESD [5]. However, with TA-ESD the perforation rate was significantly lower, and the procedure time was significantly shorter in the area of the greater curvature where gastric ESD is thought to be most difficult. Those results support the concept that TA-ESD is useful in a difficult location or situation.

The same Japanese group conducted an RCT for esophageal cancer (CONNECT-E Study Group) and showed a significant advantage of TA-ESD compared to C-ESD in the procedure time [6]. There was no difference in perforation rate as there was no perforation in either group. This might be because esophageal ESD is currently frequently performed in these Japanese referral centers.

In our opinion, TA-ESD should always be recommended for nonexpert or for Western doctors who are not experienced in ESD because the direct visualization of the dissection plane and the good traction reduce the complication rate and procedure time. One of the limitations of the meta-analysis under discussion here was that the authors were not able to analyze the “endoscopist experience” variable. Because TA-ESD is expected to be especially useful for nonexperts in ESD, future studies should consider the relationship between this variable and the main outcomes, in particular in terms of safety. The high perforation rates in some initial reports of ESD from western countries could conceivably have been significantly lower had TA-ESD been applied.

Only single-center RCTs have been reported with regard to colorectal ESD, but all studies have revealed the usefulness of TA-ESD, including the clip with nylon line method [7] and the S – O clip traction technique [8]. Even amongst all colorectal ESDs, rectal procedures, especially in the lower rectum, are different, being relatively easier because of the lower risk of perforation and the easy access for the scope. The limitation in the colorectum is that the lowest-cost methods of traction, using clips with nylon or dental floss, are difficult to apply in the proximal colon and use of the S – O clip is necessary. This clip can be used in any location, including the proximal colon or other parts of the gastrointestinal tract, but at present it is commercially available only in Japan and each clip costs more than 50€. Thus in the West, rubber band traction or nylon ring traction is used in proximal colon ESD [3] [4].

In summary, the most important considerations for ESD should be safety and effectiveness, followed by procedure time and cost. From this point of view, TA-ESD is always recommended to ensure that ESD cases are less technically challenging, despite some expense. According to the study of Su et al., the number of patients needed to treat (NNT) with TA-ESD to prevent a perforation would be 20 – 25 for esophageal and colorectal ESD, in non-Western series. Smaller NNTs would be expected in Western series with non-experts in ESD.

It is possible that C-ESD is usually fine for ESD experts, providing similar results to TA-ESD. This may also be the case for simple ESD procedures even when performed by non-experts. However TA-ESD has an important role especially in difficult procedures, such as gastric ESD in the greater curvature, fibrotic esophageal ESD, and cecal or proximal colon ESD.

At the Japan National Cancer Center Hospital (NCCH), we routinely use the dental floss traction method for every esophageal ESD in order to reduce procedure time, the same traction-assisted method for difficult gastric ESDs such as in the greater curvature of the middle and upper gastric body, the S – O clip for all cecal ESDs, and dental floss traction for challenging rectosigmoid cases.

In our opinion, this study is a valuable report: the systematic review that includes several RCTs demonstrates with high confidence the effectiveness of TA-ESD.

Publication History

Article published online:
22 April 2020

• References

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