Endoscopic submucosal dissection – just add water(jet)?

Endoscopic submucosal dissection (ESD) is an exciting technique – it holds the promise of completely removing gastrointestinal cancers using a minimally invasive endoscopic approach. ESD allows for en bloc removal of large (superficial) gastrointestinal lesions while respecting oncological principles. At the same time, the technique is far less invasive than the alternative surgical options. ESD was pioneered in Japan in the 1990s and, since then, has gained recognition worldwide as a treatment option for early gastric, rectal, and esophageal neoplasias. ESD for duodenal and colonic lesions is less frequently performed due to the higher risk of complications such as perforation and bleeding.

Preconditions for endoscopic resection were first described in the Japanese Society of Gastrointestinal Endoscopists (JSGE) classification. In 2002 an international consensus conference resulted in the Paris classification, which reflected and expanded on the structure and principles of the JSGE classification [1]. In both classifications, the endoscopic resection of gastrointestinal malignancies has limits, depending on the depth of mural invasion, tumor differentiation, and the potential risk of tumor cells in the lymphatic system.

Whereas ESD has become a standard technique in Asia, with excellent results, adoption in the Western world remains limited. A large French multicenter study published in 2011 reported sobering results for ESD: en bloc resection was possible in 77 % of patients, and complete R0 resection was achieved in 73 %. The median procedure time was 105 minutes, and short-term morbidities occurred in 29 % of patients, including a perforation rate of 18 % [2]. A recent study reporting outcomes for rectal ESD showed an en bloc resection rate of 64 %, an R0 resection rate of 53 %, and an overall perforation rate of 18 % [3]. This study was temporarily suspended because of initial perforation rates of 34 %; after study modifications, the en bloc resection rate increased from 52 % to 82 %, and the perforation rate decreased from 34 % to 0 %.

In the current issue of Endoscopy, Zhou et al. report results from a prospective, randomized, controlled trial comparing water-jet-assisted ESD with “conventional” ESD. The study included 117 patients enrolled at one Chinese center (n = 99) and one German center (n = 18). Patients were prospectively randomized to one of the two ESD techniques. The primary outcome was procedure time, and the authors found that by using water-jet-assisted ESD, the procedure times were reduced by > 20 % (mean procedure time: water-jet group 27.5 minutes vs. 35.0 minutes in the conventional group). Other outcomes such as R0 resection and complication rates, did not differ significantly between the groups.

The study presents robust data from a prospective, randomized, controlled trial enrolling a large number of patients, with excellent outcomes for ESD in general. En bloc resection rates were 100 % for the water-jet-assisted technique and 98 % for the conventional technique. R0 resection rates were also excellent, with 95 % for the water-jet-assisted technique and 90 % for the conventional technique, and perforation rates remained very low (2 % and 3 %, respectively). In this context, improvement of technical aspects, such as the combined water-jet-assisted ESD instrumentarium, helped to make ESD more attractive by reducing both the number of instrument exchanges required during ESD and the mean procedure time. However, it is notable that results for both ESD groups are excellent, and that a mean procedure time of 35 minutes for conventional ESD can be considered fast rather than unacceptably long.

There are other important factors that have profoundly influenced the outcomes for ESD in this study and in general. Both centers had very high ESD case volumes (China > 1000, Germany > 80), and only selected endoscopists with excellent expertise and experience performed the study procedures. Furthermore, the patient enrollment was also considerably higher for the center with higher annual ESD caseload (85 % of all study cases were enrolled in China). Although these methodological preconditions might have influenced outcomes towards high R0 resection and low complication rates, the excellent results for ESD from this large study with a very robust design remain and demonstrate what can be achieved by using ESD. However, the current variety and availability of different knives, electrocautery settings, injection fluids, transparent caps, endoscopes, methods to sedate a patient, and the different approaches in endoscopy units around the world, result in a multitude of combinations available to perform an ESD procedure. In addition, it is difficult to determine the definition of “conventional ESD”. Therefore, there remains considerable scope to further explore and research the field of “conventional” vs. “optimized” ESD techniques.

Although consensus on the “best” ESD technique has yet to be reached, it becomes increasingly evident that the combination of excellently trained endoscopists, high-volume experience, and continually improved accessories all help to push ESD ever closer to the ideal behind the technique – to provide a safe and minimally invasive endoscopic technique for the efficient removal of superficial gastrointestinal cancers according to oncological principles.

• References

• 1 The Paris endoscopic classification of superficial neoplastic lesions: esophagus, stomach, and colon: November 30 to December 1, 2002. Gastrointest Endosc 2003; 58
• 2 Farhat S, Chaussade S, Ponchon T et al. Endoscopic submucosal dissection in a European setting. A multi-institutional report of a technique in development. Endoscopy 2011; 43: 664-670
• 3 Rahmi G, Hotayt B, Chaussade S et al. Endoscopic submucosal dissection for superficial rectal tumors: prospective evaluation in France. Endoscopy In press 2014.
• 4 Zhou PH, Schumacher B, Yao LQ et al. Conventional vs. water-jet assisted endoscopic submucosal dissection in early gastric cancer: a randomized controlled trial. Endoscopy 2014; 46: 836-843