Mucosal rection generally involves the u of a snare to rect the tissue, whereas ESD
utilizes a discting ‘knife’. Becau of the u of the snare, inevitably in the EMR
techniques, a pudopolyp must be formed either by suction or by utilizing a submucosal
injection and cushion followed by banding. In ESD, fluid must be introduced into the
submucosa to define the submucosal space to allow visualization of this area for careful
manual disction. In this article, we will review the indications and complications
associated with both of the techniques.Indications for procedure EMR and ESD are both targeted toward mucosal lesions [1••]. Therefore, it is not surprising that mucosally bad neoplastic lesions such as esophageal squamous cancers,adenocarcinomas associated with Barrett’s esophagus, and gastric cancers are the most common targets for this therapy in the upper gastrointestinal tract [2–4]. Less common usages would be for the removal of submucosal lesions such as leiomyomas or GIST [5].Most of the submucosal lesions are approached with ESD, which allows the endoscopist to carefully disct the tissue (e Table 1).Lesions are grossly classified according to the appearance of the lesion (e Fig. 1) [6]. Most often, lesions that are elevated or raid are most amenable to mu
cosal rection techniques [7]. Lesions that are ulcerated or depresd are less amenable becau they have a tendency to invade deeper and to have inflammatory respon that makes it difficult to parate the mucosa from the sub-mucosa.Other factors that determine the indications for rection include the size of the lesion.Generally, lesions that are smaller than 1 cm to perhaps 1.5 cm in diameter are better managed with EMR techniques simply becau the are just as effective as submucosal disction and can remove the lesions en bloc [3]. In lesions larger than this and up to 3–4cm in size, ESD should be considered. Lesions larger than 4 cm often have deep invasion
and high risk of metastatic lesions. The need to do ESD in addition to radiation and
chemotherapy to treat an early-staged cancer has not been shown. ESD has been ud after
chemoradiation to complete removal of tumor in very small ca reports with reasonable
short-term results [8]. EMR can also be ud for this application in smaller lesions especially
given the tendency for the submucosal tissue planes to be more difficult to identify after
chemo-radiation. In a small cohort of 21 patients, overall survival was 49% at 5 years using
EMR as a salvage therapy after chemotherapy and radiation [9].
In the treatment of neoplasia, lesions that have high risk of metastasis are not usually felt to
be candidates for the rection techniques. The would include the lesions’ size, evidence
of neural invasion or angiolymphatic invasion, lymphocytic invasion, and evidence of deep
sub-mucosal invasion [10,11].
Asssment prior to rection
The current staging of superficial neoplasms includes careful white light endoscopy to
visualize the area of neoplasia and to detect whether there is any concurrent dia. There is
a need to identify the margins of the neoplasia, which often are only apparent with
enhancement. This is often enhanced by using chromoendoscopy with topical contrast
agents such as indigo carmine, methylene blue, toluidine blue, acridine orange, and crystal
violet [12]. All of the dyes are absorbed by the mucosa with the exception of indigo
carmine, which is strictly a contrast dye. The absorptive dyes are less commonly ud, as
some of the agents, such as acridine orange, will bind to the DNA within cells. This
provides good nuclear contrast but may be carcinogenic. Optical methods of providing
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contrast include narrow band imaging or autofluorescence imaging which permit
visualization of vascular and mucosal patterns [13••,14].
Endoscopic ultrasound is usually performed to stage the depth of the lesion. This is probably its weakest point in terms of reproducibility and validity. Often endoscopic ultrasound can only stage superficial lesions correctly about 40–60% of the time [15]. The need for endoscopic ultrasound for performance of mucosal rection is limited [16,17]. When performed for staging, it is apparent that
high-frequency ultrasound probes are needed to stage early lesions, whereas the echoendoscopes are needed for investigation of lymph node status. However, this is not necessary for low-risk lesions such as lesions smaller than 1 cm without ulceration that lift easily with injection prior to rection. Other imaging techniques such as positron emission tomography (PET) or computed tomography (CT) scans are done to look for meta-static dia. It can be argued that in patients with very superficial cancers,this is not necessary, although it is often part of clinical practice to perform staging imaging studies for all neoplastic lesions.Techniques of rection: endoscopic mucosal rection In the United States, the most common way to perform EMR is either using the band ligation technique or cap technique. Both of the techniques involve the u of suction through an endoscope with a friction fitted cap to create a pudopolyp. The cap technique (Olympus Corporation in Center Valley, Pennsylvania, USA) and band technique (Cook Medical, Indianapolis, Indiana, USA) are the two available devices.In general, the band ligation device, which is very similar to a variceal banding device, is the most easily applied. This is becau it can be done without any preinjection and the technique itlf is very similar to variceal ligation. The area of abnormality is identified,suctioned into a cap similarly to variceal banding, and the band is relead to capture the area of abnormality (Fig. 2). A hexagonal snare can then be ud to remove the area of tissue
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using a pure coagulation tting. The snare can be applied above the band, below the band,
and it can even cut through the band. The tissues are generally retrieved after multiple
rections are performed using an endoscopic polyp retrieval basket. As this technique
requires that the tissue be easily movable to suction into the cap, it is really best ud when
the patient is initially evaluated and has not had prior treatment or scarring to the esophagus
or stomach. Such scarring can prevent the band from capturing the tissue. After six
rections are performed, another device must be deployed if additional rections are
needed. The major strengths of this device are ea of u, ability to perform multiple side-
by-side rections to piecemeal remove large areas of mucosa, and the ability to maintain a
rection snare within the endoscope (if the banding device is ud in combination with a
therapeutic endoscope). The weakness are the lack of ability to localize site of removal of
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a single rection unless the endoscope is withdrawn, the need to have fairly pliable tissue in
order to rect a lesion, and the decread field of view that occurs with the bands obscuring
lateral vision. It is for the latter reason that the author usually recommends preinjection of a
dilute epinephrine (1 : 200 000) saline solution to both confirm the pliability of the tissue
and decrea any bleeding that may obscure visualization.
The cap technique was actually developed first and involves using a cap with a lip on the
distal end. The targeted lesion is lifted with a submucosal injection of a saline epinephrine
solution. This aids in permitting safe removal of the tissue above the muscularis propria. A
snare can be positioned around the lip and then tissue suctioned through the opening in the
cap and then the snare clod. The most difficult part of this procedure is placement of the
snare around the lip of the cap (Fig. 3). Once the snare is clod around the suctioned tissue,
the snare is pushed out of the cap and the tissue ‘tugged’ to asss whether the tissue
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captured actually is only mucosa or if traction appears to move the entire wall, that there is a
possibility that the muscularis propria is also entrapped (Fig. 4). The technique itlf
requires more experience and is usually more cost-effective when applied in situations
where fewer rections are required. In addition, the cap technique is uful when the patient
returns for additional mucosal rection, as the cap technique can rect tissues that cannot
be suctioned as far into the barrel as required for the banding technique. The tissue is
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suctioned into the cap and the endoscope is withdrawn. The strengths of this technique are
the ability to decrea the cost if only one or two rections are required, the ability to rect
tissues that are less flexible, and the ability to retrieve the targeted tissue. The weakness
are the difficulty in positioning the snare around the tip of the cap, the need to re-intubate
the patient should a cond rection be required, and both the techniques have been shown
to rect approximately the same size of tissue.
Endoscopic submucosal disction
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This technique is also popularized in Japan for en bloc rection of superficial neoplasms. It
is really indicated for the large raid or flat lesions of the stomach or esophagus. Generally
speaking, the area of interest is first carefully marked using cautery, as once the rection
begins, it is difficult to determine the boundaries of the lesion that needs to be removed.
After this is done, a viscous fluid is injected submucosally to ensure there is a cushion
underneath the lesion to allow disction. In the United States, the most common viscous
小孩子小名fluid is Gonak or hydroxypropylmethyl cellulo. A number of substances have been ud in
the past including hypertonic saline, 50% gluco, hyaluronic acid, 10% glycerol, sodium
alginate solution, and fibrinogen, but most have been replaced with cellulo solutions
becau of their decread cost and commercial availability in the United States. It has been
reported that hydroxypropylmethyl cellulo can produce inflammation when injected sub-
mucosally. The solutions usually have a dye such as indigo carmine added to them to allow
the endoscopist to quickly visualize the submucosal space which will be stained blue.
The cutting tools themlves are similar in dimensions to a needle knife but often have more
angulated tips or a nonconducting tip to prevent inadvertent puncture of the muscularis
propria or a blood vesl. The discting knives are ud to grab and then cut through the
sub-mucosal fibrous tissue. The cutting devices themlves range from triangle tip knife,
insulated tip knife, flex knife, fork knife, hook knife, needle knife, and flush knife [18–26]
(Fig. 5). All of the knives have been invented by mainly Asian physicians to enable rapid
ESD. The variety of available knives often reprents improvements in various phas of the
disction. The insulated tip knife and the flex knife were designed to decrea the risk of
perforation from the sharp needle knife, which was initially ud. The triangle tip knife has a
sharp edge to permit better mucosal incision but has a blunt tip as well to permit cautery as
well as disction. The flush knife has a channel in the center that allows flushing of water
to enhance visualization in ca of bleeding. None of the knives have been clearly shown to
be superior to the other and em to yield similar results in expert hands. ESD can be
completed with a single knife, but often for expediency can be completed with a snare after
the lesion is incid, circumscribed and discted free of the submucosal for the most part.
Cautery is most commonly applied with an electrocautery unit using a blended current with
primary coagulation. Puld electrocautery is commonly ud to allow greater control.
冰箱漏水In the past, it was described that the submucosal disction had to be performed by first
circumferentially cutting around the lesion (Fig. 6). At the current time, a number of experts
now inci an area distally and proximally around the lesion, leaving the lateral margins
intact to retain more of the viscous fluid. Once the tissue is more than micircumferentially
discted, it retracts revealing the submucosa. The endoscope has a small flexible disction
cap fitted as shown in Fig. 6, which permits the ur to lift the edge of the disction and
inrt a cutting knife. The results of this treatment can be en in Fig. 7, in which a large 4-
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cm gastric cardia lesion has been removed. Although this can be done with standard
diagnostic endoscopes, for areas such as the cardia, which can be difficult to access,
specialty endoscopes have also been created such as the multibending endoscope which can
好收吾骨瘴江边flex at two different points allowing easier access to lesions that must be approached in the
retroflexed position [27].
Comparisons of endoscopic submucosal disction and endoscopic mucosal rection
Although there are no randomized prospective large studies of ESD and EMR for neoplastic
lesions, veral retrospective cohort studies have been reported. In early gastric cancer, it
appears that ESD is significantly more likely to result in higher en bloc rection rates (93
versus 34%) and higher rates of being recurrence free at 5 years (100 versus 83%) [28••]. In
retrospective analysis, gastric lesions less than 1.5 cm have a high rate of complete rection
with EMR as with ESD. It has been shown in a prospective randomized study of strip biopsy
versus ESD that strip biopsy was as effective as ESD in lesions smaller than 1.5 cm [29]. A
recent meta-analysis of 15 nonrandomized studies found that ESD was superior to EMR in
all size categories including tho with lesions less than 1 cm but was associated with a 4.09
odds ratio of perforation and a 2.2 odds ratio of having bleeding [29]. In a recent large ries
of 1000 gastric cancer patients from multiple centers in Korea, the perforation rates were
found to be 1%, with a bleeding complication rate of 16% [30]. The results are
substantially higher than EMR complications from our own institution which has a bleeding
rate of 2 and a 0% perforation rate in esophageal EMR. A recent innovation with a jet hybrid
knife allows injection of more submucosal fluid during disction, which appears to
decrea risk of bleeding and perforation during ESD to levels that occur with EMR,
although this was only done in an animal model [3].Conclusion EMR and ESD are both techniques designed to remove large areas of tissue. EMR appears
to be more appropriate for smaller lesions (<1.5 cm in diameter) and can be completed in
less time and with fewer complications than submucosal disction techniques. ESD is a
method to rect larger lesions en bloc to prerve knowledge of neoplastic invasion but is
associated with far more significant complications. Both techniques provide incread
volumes of tissue to permit better asssment of risk factors for tumor metastasis and
establish a definitive diagnosis. EMR can be ud to remove larger lesions in a piecemeal
fashion but leads to incread recurrence when applied in this way. The instrumentation is
different for each of the techniques, with the EMR more likely to be performed with a snare,
whereas the ESD requires a cutting device and potentially a different type of endoscope to
access more difficult to reach areas.
Acknowledgments
Rearch support was from National Cancer Institute Grants R01CA097048, R01CA111603, and R21CA122426.
References and recommended reading
Papers of particular interest, published within the annual period of review, have been
highlighted as:
• of special interest
•• of outstanding interest
1••. Nelson DB, Block KP, Bosco JJ, et al. Endoscopic mucosal rection: May 2000. Gastrointest
Endosc. 2000; 52:860–863. This is a summary of the technology in endoscopic mucosal
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