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A plastic cap for mucosectomy (MH-597, Olympus Optical Co., Ltd, Tokyo, Japan) with an outer diameter of 17 mm and a length of 15 mm will be preloaded on the tip of the colonoscope. Inside the distal end of the cap there is a gutter which positions the opened polypectomy snare.

After submucosal injection, the cap will be applied against the lesion which will be aspirated by "controlled suction", avoiding excessive protrusion of tissue in order not to trap the muscular layer.

The tissue will then be gripped with the snare and resection will be performed. A specific polypectomy snare which can be adapted into the gutter of the cap will be used (SD-221U-25, Olympus Optical Co., Ltd, Tokyo, Japan).

The resection will be performed using a standard polypectomy snare, which diameter will be chosen according to the size of the lesion, after lifting the lesion from the underlying layers with a submucosal injection of liquid.

endoscopic mucosal resection of colonic lesions with a plastic cap for mucosectomy

cap for mucosectomy

endoscopic mucosal resection of colonic lesions with standard inject and cut mucosectomy

standard snare for polypectomy

Antonella De Ceglie, MD

Mario Marini, MD

Mario Marini, MR

Massimo Conio, MD

Raffaele Manta, MD

"Lateral Spreading Tumors" (LSTs) are dysplastic lesions whose protrusion within the lumens the colon is not more than twice as compared to the surrounding non-dysplastic mucosa.

They can be divided into two groups:

Granular type (LST-G) and Non Granular type (LST-NG) Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are currently the most used techniques to resect this type of lesions. Compared to other methods of tissue ablation, EMR allows to carry out the histological evaluation of the resected fragments and ESD of the lesion in toto ("en bloc") EMR is currently the most used technique for removal of LST, but for lesions of ≥ 30 mm the resection is performed "piecemeal", i.e. fragmentary. This can compromise an adequate histological evaluation of the lateral and deep margins of the lesion.

Colonic EMR (EMR-S) is usually performed using a polypectomy snare, after lifting the lesion from the underlying layers with a submucosal injection of liquid (EMR standard or "inject-and-cut"). The aspiration of the lesion inside a plastic cap preloaded on the tip of the colonoscope ("cap-assisted EMR" - EMR-C) is almost exclusively used for the treatment of gastric and esophageal lesions. Its use for lesions of the colon and duodenum has been reported in limited experiences The principal aim of this study is to evaluate the efficacy and the safety of the EMR-C for the removal of large colonic LST-G and LST-NG, comparing it with EMR-S.

Colorectal carcinoma (CRC) is the second cause of death for cancer in industrialized countries, with annual incidence and mortality of about one million and 500.000 case respectively.

It's well known that most of CRC follow the path adenoma-carcinoma: early diagnosis and endoscopic removal of colonic polyps has been proved to be useful in preventing cancer.

Most of colorectal polyps are smaller than 1 cm and can be successfully resected with a standard polypectomy. However, between 0.8% and 5% of patients develop sessile polyps or lesions larger than 20 mm, of which removal can be difficult, requiring high endoscopic experience.

Recent prospective studies report that 7%-36% of CRC have a flat or depressed morphology and are more likely to infiltrate the submucosa compared with polypoid ones.

A univariate analysis has proved that the size of the lesion is the only significant risk factor associated with malignant evolution.

Contrary to sessile polyps (SP) that are protruding lesions without a peduncle and whose base has almost the same dimension of the head, "Lateral Spreading Tumors" (LSTs) are dysplastic lesions whose protrusion within the lumen is not more than twice as compared to the surrounding non-dysplastic mucosa. According to Kudo classification they are larger than 1 cm in size, slightly elevated and extending laterally along the intestinal wall.

They can be divided into two groups (according to Paris Classification, 2005, updated for the colon in Kyoto Classification 2008):

* Granular type (LST-G) characterized by nodular aggregates and sub-classified into homogeneous (0-IIa according to Paris Classification) and mixed nodular (0-IIa, 0-Is + IIa, 0-II+ Is) subtypes.
* Non Granular type (LST-NG) characterized by a non nodular surface and sub-classified into elevated (0-IIa) and pseudo-depressed (0-IIa + 0-IIc, 0-IIc +0- IIa) subtypes.

The risk of developing cancer is different between the two types (57.7% in LST-NG vs 32.7% in LST-G). LST-NG are more likely to invade the submucosa compared to LST-G (14% vs 7%). Within the LST-G group, lesions with a mixed nodular morphology have a greater tendency to infiltrate the submucosa compared to the homogeneous ones.

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are currently the most used techniques to resect this type of lesions. Compared to other methods of tissue ablation, EMR allows to carry out the histological evaluation of the resected fragments and ESD of the lesion in toto ("en bloc").

EMR allows the resection of superficial neoplasia of gastro-intestinal tract (GI) confined to the mucosa, in the absence of vascular and/or lymphatic invasion.

ESD compared with EMR allows to remove "en bloc" lesions ≥20 mm in size. It should be preferred for lesions with higher risk of invasiveness or when the removal of the deepest layers or of the whole submucosa is desired, despite the size of the lesion. However, ESD is a complex procedure which requires a long training period and it is associated with higher risk of perforation compared with EMR (6.2% vs 1.3%). Furthermore, ESD requires a longer execution time.

Therefore, EMR is currently the most used technique for removal of LST, but for lesions of ≥ 30 mm the resection is performed "piecemeal", i.e. fragmentary. This can compromise an adequate histological evaluation of the lateral and deep margins of the lesion.

Piecemeal resection increases the risk of residual disease that ranges from 12% to 20% compared with 5% described after "en bloc" removal while the percentage of recurrence reported for polypoid lesions ≥ 20 mm is on average 25% (21) and reaches 55% in some studies.

Colonic EMR is usually performed using a polypectomy snare, after lifting the lesion from the underlying layers with a submucosal injection of liquid (EMR standard or "inject-and-cut"). The aspiration of the lesion inside a plastic cap preloaded on the tip of the colonoscope ("cap-assisted EMR" - EMR-C) is almost exclusively used for the treatment of gastric and esophageal lesions. Its use for lesions of the colon and duodenum has been reported in limited experiences.

The advantage of diagnostic "cap-assisted colonoscopy" (CAC) is the higher chance of reaching cecum even by less experienced endoscopists in a shorter time, with less pain for the patients and a better observation of the mucosa behind the folds and at the flexures. There are not enough concordant data about the percentage of missing lesions, especially if small in size (27, 28). The cap makes the position of the instrument more stable during standard "inject-and-cut" technique (EMR-S), and reduces execution time. However, the realization of the EMR-C for colonic lesions isn't reported (29).

The use of EMR-C in colon is controversial because of the risk of entrapping the muscular layer in the polypectomy snare with risk of perforation.

The advantage of using the cap is represented by the possibility to perform mucosectomy of lesions located in difficult positions (between haustra, near or involving the ileo-caecal valve), thanks to the improved visibility on the operative field.

Our group has reported a 4% of residual disease/recurrence rate, much lower than those reported by other authors who performed EMR-S. We had a perforation and bleeding rate of 0% and 7% respectively vs 0.4% and 11% as reported in literature with EMR-S.

More recently, a study of 134 lesions treated with EMR-C reported a recurrence rate of 1.8% on 82 lesions treated, with a mean of 4.2 months follow-up.

The principal aim of this study is to evaluate the efficacy and the safety of the EMR-C for the removal of large colonic granular and non-granular Lateral Spreading Tumors (LST-G, LST-NG), comparing it with EMR-S.

Patients with colorectal LST-G/NG ≥30 mm will be included. Patients who refuse endoscopic follow up will be excluded from the study. The total enrollment period will be 6 months Endoscopic evaluation in patients without invasive carcinoma will be performed at 3, 6 and 12 months, and then annually Follow-up period will last 12 months from the enrollment of the last patient.

Will be defined as:

Residual lesion: the presence of adenomatous tissue endoscopically visible at follow-up colonoscopies within the first year from EMR.

Recurrent lesion: the presence of adenomatous tissue endoscopically visible after 2 (at 3 and 6 months from EMR) previous negative colonoscopies.

EMR-C VS EMR-S in Colonic Lateral Spreading Tumors Treatment (LST)

"Cap-assisted" Endoscopic Mucosal Resection vs Standard "Inject and Cut" Endoscopic Mucosal Resection for Large Colonic "Lateral Spreading Tumors" Treatment: a Randomized Multicentric Study.

Patients with non invasive lesions will undergo follow-up colonoscopies at 3, 6, 12 months and thereafter annually after both EMR-C and EMR-S..

The presence of adenomatous tissue endoscopically visible at follow-up colonoscopies within the first year from EMR will be considered as residual lesion.

The presence of adenomatous tissue endoscopically visible after two previous negative colonoscopies will be defined as recurrence. "

Complications are defined as:

intraprocedural early: within 48 hours; late: after 48 hours from the endoscopic procedure;

Type of complications:

Bleeding (intraprocedural, loss of blood from rectum; Perforation (documented with the presence of free air in abdomen by RX and/or CT); Post polipectomy syndrome (abdominal pain with or without fever, without any free air in abdomen reported by radiological investigations)

Study title	NCT ID	Conditions	Interventions	Eligibility	Organization	Link
EMR-C VS EMR-S in Colonic Lateral Spreading Tumors Treatment (LST)	NCT03498664	Endoscopic Muco...	cap for mucosec... standard snare ...	18 Years -	Azienda Ospedaliera Universitaria Senese
EMR-C VS EMR-S in Colonic Lateral Spreading Tumors Treatment (LST)	NCT03498664	Endoscopic Muco...	cap for mucosec... standard snare ...	18 Years -	Azienda Ospedaliera Universitaria Senese

Spots Global Cancer Trial Database for standard snare for polypectomy