Lesions at the appendiceal orifice – the Achillesʼ heel of endoscopic resection?Referring to Ichkhanian Y et al. pages 16–24
Since the introduction of endoscopic full-thickness resection (EFTR) using the full-thickness resection device (FTRD), many studies have investigated the technique for its efficacy and safety in various indications. However, it is a matter of debate as to whether it should be used for endoscopic resection of lesions involving the appendiceal orifice.
“In the current study, 58 % of lesions were deemed to have “deep extension into the orifice.” However, the R0 resection rate in the current study was as high as 93 %. These favorable results indicate that FTRD does indeed allow complete resection, even of advanced lesions.”
In the current issue of Endoscopy, Ichkhanian and colleagues report on the outcomes after EFTR for appendiceal lesions . Data were collected retrospectively from 18 centers, with 66 patients included. En bloc resection with the FTRD could be achieved in 89 % of cases. This result is not surprising as previous studies have already indicated that the success rates for EFTR of appendiceal lesions are comparable with those reported for other sites in the colorectum . But how about resection completeness? As the authors correctly point out, the difficulty lies in the anatomical properties of the appendiceal region. In cases with deep involvement of the appendiceal orifice, we usually cannot see the maximum extent of appendiceal involvement before commencing the procedure. In the current study, 58 % of lesions were deemed to have “deep extension into the orifice.” However, the R0 resection rate in the current study was as high as 93 %. These favorable results indicate that the technique does indeed allow complete resection, even of advanced lesions.
The authors chose the R0 resection rate as the primary end point for their study; however, the risk of appendicitis may be even more interesting. When we perform endoluminal resection of lesions at the appendiceal orifice with the FTRD system, we intentionally close the appendiceal orifice with the clip. A common understanding of the pathogenesis of acute appendicitis is that obstruction of the orifice ultimately leads to inflammation.
The WALL RESECT study was the first prospective trial to report on a reasonably sized subcohort of 34 appendiceal lesions resected with the FTRD system . The rate of appendicitis was surprisingly low (8.8 %). Similarly, the German FTRD Registry included data from 89 patients with lesions at the appendiceal orifice . The rate of appendicitis was 8 % (n = 7), with 3/7 patients requiring surgery. However, in both studies the proportion of patients who had undergone previous appendectomy was not reported, so the real risk of appendicitis may have been underestimated. Recently, Schmidbaur and colleagues published a retrospective multicenter study on 50 patients undergoing EFTR at the appendiceal orifice . In all 50 patients, the appendix was in situ prior to EFTR. Acute appendicitis occurred in a total of seven patients (14 %), with three patients requiring consecutive appendectomy (42 %). In the current study, 10 out of 58 patients with no history of appendectomy developed acute appendicitis, corresponding to a rate of 17 %. Of these, six patients (60 %) required emergent appendectomy.
At this point, it is pertinent to say that we need larger studies, but I think the two studies by Schmidbaur and Ichkhanian show quite clearly that about 15 %–17 % of patients will develop appendicitis and about half of these cases will need emergent appendectomy. To me, the important question is now: can we accept this risk and recommend EFTR for benign appendiceal lesions to our patients? To answer this question, we need to look more closely at the alternatives to EFTR. Endoscopic mucosal resection (EMR) has been described as being feasible for lesions involving the appendiceal orifice. Tate et al.  reported good results for EMR; however, for most lesions in their series, endoscopic management was not even attempted because of deep extension into the appendiceal lumen or involvement of more than 50 % of the circumference of the appendiceal orifice. For such advanced lesions, resection with the FTRD may be the ideal endoluminal approach because the resection can be extended to deeper parts of the orifice by pulling the lesion into the cap. For lesions with a diameter > 2 cm, EFTR can also be combined with prior EMR in a “hybrid” technique to ensure complete lateral resection .
Surgery is considered by most authors to be the gold standard for the treatment of neoplasm at the appendix. However, surgical resection is limited by the difficulty of ensuring a negative lateral margin without compromising the ileocecal valve. A study by Abdalla and colleagues reported on surgical resection of benign lesions at the appendiceal orifice that had been classified as not amenable to endoscopic resection . Morbidity after cecal wedge resection was as high as 20 %, with a requirement for repeat surgery in 4 % of cases. If more extensive operations, such as ileocecal resection or right hemicolectomy, are necessary, the morbidity and complication rates are even higher . Therefore, the rate of severe complications after surgical resection may not be significantly lower than for EFTR.
Although the study by Ichkhanian et al. has shed further light on this problem, several questions remain unanswered. It is unclear why some patients develop appendicitis and others do not. Although the authors tried to identify risk factors, criteria for the selection of patients are still unknown. Moreover, apart from immediate adverse advents, we know almost nothing about the long-term consequences of “clip-assisted” EFTR at the appendiceal orifice. What happens to the appendix? Will some patients develop a mucocele owing to obstruction of the orifice? How should we follow up these patients? The current study does not give answers to these questions as it included a relatively short and largely incomplete follow-up.
How should we now proceed in our clinical practice? We are of course obliged to thoroughly inform our patients about the risks of the procedure and about treatment alternatives. If the lesion is too advanced for “conventional” endoscopic resection, we can suggest EFTR as a valuable alternative to surgical resection. However, I do not agree with the authors that EFTR is a good choice for patients considered to be poor candidates for surgery. As shown in the current study, we will put these patients at considerable risk of future surgery because of acute appendicitis, and the outcome of emergency surgery will potentially be worse compared with that of an elective surgical procedure in high risk patients.
24. November 2021 (online)
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