Endoscopic resection of duodenal adenomas: endoscopic mucosal resection or endoscopic submucosal dissection?

Although the incidence of malignant duodenal neoplasms is low, duodenal adenomas are precursor lesions to cancer [1] and endoscopic resection is therefore justified if it can be performed safely. Multiple reports have demonstrated that endoscopic mucosal resection (EMR) of nonampullary duodenal adenomas – typically performed by standard snare polypectomy after submucosal fluid injection – yields acceptable results with regard to both safety and efficacy. Delayed bleeding is the most common complication of duodenal EMR, occurring in 0 – 30 % of cases [2] [3] [4] [5]. Endoscopic treatment utilizing clip placement or cauterization is usually effective, although many cases also resolve spontaneously [2]. Perforation is a rare complication of EMR, occurring at a rate of 0 – 3 % in most series. Most perforations occur with resection of larger lesions: for example, in one report there were no perforations in 31 resections of lesions < 30 mm compared with two perforations in 19 lesions ≥ 30 mm [6]. A limitation of EMR is recurrence of lesions on follow-up endoscopy, which is observed in 0 – 37 % of cases [7]. Although data are sparse, endoscopic treatment is successful for most recurrences [7].

Endoscopic resection of duodenal adenomas is technically challenging for several reasons, including the tight space, angulation, and relatively poor lifting with submucosal injection. The rich vascular supply increases the risk of bleeding, and the thin muscle layer is more prone to perforation. Because duodenal adenomas are uncommon, reported endoscopic resection series are small, and even in large centers endoscopists may not have sufficient volumes to achieve a high comfort level. Despite these challenges, duodenal EMR is practiced widely throughout the world and the technique is relatively straightforward to teach and learn. However, as in other areas of the gastrointestinal tract, EMR is frustrating for endoscopists who strive toward achieving the holy grail of endoscopic resection – an R0 resection, where the entire lesion is resected in one piece, with a rim of normal surrounding mucosa that unequivocally demonstrates complete removal of the lesion. With EMR, lesions larger than 20 mm usually cannot be removed in one piece, and even smaller lesions are typically not resected with an intact rim of normal mucosa, so that the assessment of a complete resection is generally done by endoscopic visualization rather than histologically.

In the stomach, where these limitations of EMR are clinically important, EMR has been supplanted by endoscopic submucosal dissection (ESD). Gastric ESD is now the standard of care for treatment of early gastric cancer, as it permits safe and effective treatment with significantly fewer deleterious outcomes due to recurrence or incomplete treatment compared with EMR [8]. It is natural, then, to ask whether these technical advances are applicable to the duodenum. Unfortunately, multiple small case series have now been published illustrating the pitfalls associated with duodenal ESD.

Even in expert hands, successful duodenal ESD is considered a technical tour de force. The narrow lumen, paradoxical motion of the endoscope tip, rich vascular network, and thin muscle layer all conspire to make the procedure difficult and risky [9]. Several small reports, primarily from expert centers in Japan and Korea, have demonstrated high rates of complete resection with essentially no risk of recurrence [10] [11] [12]. However, even at these expert centers, perforation rates have ranged from 6 % to 50 % [11]. Intraoperative duodenal perforations are often difficult to repair endoscopically because of the tortuous anatomy and the fragility of the tissue. Even if a perforation is repaired successfully using clips, the closure may not be reliable enough for endoscopic resection to continue, as is often done in the stomach. Worse yet, there is also a significant incidence of delayed perforation, which typically cannot be managed endoscopically, even if the patient is kept in hospital for several days for observation after the procedure. Although one might naively hope that a small duodenal retroperitoneal perforation might be better tolerated than perforations elsewhere in the gastrointestinal tract, anecdotal reports suggest that even when patients are successfully managed conservatively, recovery may necessitate multiple weeks in hospital [13].

Against this background, the report by Nonaka et al. in this issue of Endoscopy provides insight into the long term outcomes of a large number of patients treated at the National Cancer Center Hospital in Tokyo, Japan [14]. A total of 121 duodenal lesions were treated over a period of 13 years. The median lesion size was small (12 mm), but the series included lesions up to 50 mm in diameter. Of the 121 lesions, 113 were treated conventionally by EMR or polypectomy. The standard inject and snare EMR technique was used most often. Eight patients were treated by ESD. There were no perforations in patients treated by EMR or polypectomy. There was a relatively low rate of delayed bleeding in the study: 12 % overall, all of which occurred in the EMR group. All of the bleeds were successfully treated by repeat endoscopy, with only one patient requiring blood transfusion. The authors attribute the low bleeding rate in part to prophylactic clipping, which was performed routinely except in a relatively small number of patients in whom it was deemed technically impossible. However, the role of prophylactic clipping is debatable, as low bleeding rates can be achieved in small lesions without routine clipping and large defects that are more likely to bleed are often impossible to close using clips [6]. More remarkable was the complete absence of local recurrence: none of the patients in this series, whether treated by EMR or ESD, had local recurrence. Only 5 % of patients were lost to follow-up, and 67 % of patients received follow-up for over 1 year after the procedure. There was no local recurrence in the EMR group despite an en bloc lesion resection rate of 63 % and an R0 resection rate of 34 %. This study therefore confirms that duodenal EMR can achieve outstanding clinical success with a very favorable complication profile and excellent long term results. It is not necessary to perform an R0 resection of duodenal adenomas to achieve successful lesion eradication. Piecemeal EMR was sufficient to achieve clinical success, even in lesions larger than 20 mm, of which only 3/14 (21 %) could be removed en bloc in this series.

What about ESD in the duodenum? Even in this center, where much of the pioneering work in gastric ESD was performed, the results in a limited number of cases were typically worrying. ESD was performed in eight lesions. One patient suffered an intraoperative perforation. The perforation was closed using clips but the patient required subsequent surgery to resect the lesion. One patient had a delayed perforation on the day after the ESD and required surgical repair. The R0 resection rate was 50 %. Because of the small number of patients, it is difficult to compare these ESD results directly with those from other series, but the two worrying perforations (25 %) in the Nonaka series appear to be representative of the challenges encountered with duodenal ESD.

Where then do we stand with ESD? Although ESD can be performed in the duodenum, current results suggest that it should not be done routinely. There are a few highly proficient endoscopists who have achieved success, but the preponderance of published data suggests that technical advances are necessary to improve outcomes even at expert centers. Some centers have reported that a full or partial circumferential incision of the mucosa around the lesion is relatively safe, and may in some cases facilitate en bloc snare resection of lesions < 2 cm [15] [16]. Submucosal dissection may be aided by small-caliber-tip caps, tunneling techniques, and selected cautery knives, but at present this remains the most challenging and risky part of the procedure [9]. An effective and safe dissection method is needed. The target – a reliable R0 endoscopic resection in the duodenum – is in sight but not yet within reach. Performing ESD in the stomach is like driving an exotic sports car on a race track – it is a high performance thing of beauty. But the duodenum is more like a mountain road in the winter. With good driving skills you might survive in that exotic vehicle, but most of us are better off with a more reliable car with snow tires. An EMR will work just fine for now, thank you!

• References

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