RISK MANAGEMENT OF THERAPEUTIC COLONOSCOPY (HOT BIOPSY,POLYPECTOMY, ENDOSCOPIC MUCOSAL RESECTION AND ENDOSCOPIC SUBMUCOSAL DISSECTION)

The concept of an adenoma–carcinoma sequence has been widely accepted in the colon and rectum, contrary to that in gastric cancer. Consequently, most target lesions for endoscopic resection using these newly developed techniques are histologically assessed as adenoma or intramucosal carcinoma in adenoma. Based on results in conventional endoscopic mucosal resection (EMR), almost all remnant or recurrent tumors can be successfully managed by salvage EMR, and all materials resected by salvage EMR also showed adenoma or intramucosal cancer. These results suggest that en bloc resection is not always clinically necessary to obtain complete cure for all colorectal neoplasia. However, larger lesions tend to be resected in a piecemeal fashion; it is difficult to confirm whether EMR has been completed or not. For precise histopathological assessment of the resected specimen, endoscopic submucosal dissection (ESD) for en bloc resection is desirable, although further experience is needed to establish its safety and efficacy. The present review contains a summary of the risk management of therapeutic colonoscopy including ESD for large colorectal mucosal neoplasia, debated at the Endoscopic Forum Japan 2006, Hakone, and discussion of the problems and future prospects of these procedures.     

Colorectal endoscopic submucosal dissection: present status and future perspective,including its differentiation from endoscopic mucosal resection

Endoscopic submucosal dissection (ESD) allows en bloc resection of a lesion, irrespective of the size of the lesion. ESD has been established as a standard method for the endoscopic ablation of malignant tumors in the upper gastrointestinal (GI) tract in Japan. Although the use of ESD for colorectal lesions has been studied via clinical research, ESD is not yet established as a standard therapeutic method for colorectal lesions because colorectal carcinoma has unique pathological, organ specific characteristics that differ radically from those of the esophagus and stomach, and scope handling and control is more difficult in the colorectum than in the upper GI tract. Depending on the efficacy of endoscopic mucosal resection (EMR) and the clinicopathological characteristics of the colorectal tumor, the proposed indications for colorectal ESD are as follows: (1) lesions difficult to remove en bloc with a snare EMR, such as nongranular laterally spreading tumors (particularly the pseudo depressed type), lesions showing a type VI: pit pattern, and large lesions of the protruded type suspected to be carcinoma; (2) lesions with fibrosis due to biopsy or peristasis; (3) sporadic localized lesions in chronic inflammation such as ulcerative colitis; and (4) local residual carcinoma after EMR. Colorectal ESD is currently in the development stage, and a standard protocol will be available in the near future. We hope that colorectal tumors will be efficiently treated by a treatment method appropriately selected from among EMR, ESD, and surgical resection after precise preoperative diagnosis based on techniques such as magnifying colonoscopy.     

重视并开展内镜黏膜下剥离术的规范化操作

内镜切除术治疗胃肠道早期肿瘤正日益被接受并开展应用,包括传统的内镜黏膜切除术（EMR）和近年开展的内镜黏膜下剥离术（ESD）。EMR对于15mm以上的病灶较难做到一次切除,而整块切除标本对病理学评估至关重要,ESD正是应这一要求开展起来的新技术。对局限于黏膜层的病变,ESD并不受其大小的限制,对部分早期胃肠道肿瘤,其可取代传统的手术治疗,但ESD需要相当高的内镜操作技术,术前需要多种方法对病灶进行谨慎、全面的评估,包括范围、浸润深度等,术中、术后还可能出现出血、穿孔等严重的并发症,其发生率远高于EMR。ESD的指征、操作技巧、病理评估等方面还需要不断完善。由于ESD在早期胃肠道肿瘤的治疗上具有很多优点,值得有条件医院的内镜医师予以重视并开展这一技术。     

Endoscopic submucosal dissection of early gastric cancer

The purpose of this review was to examine a remarkable technical advance regarding the indications for and the technique of endoscopic resection of early gastric cancer. Endoscopic mucosal resection (EMR) of early gastric cancer with no risk of lymph node metastasis has been a standard technique in Japan, probably owing to the high incidence of gastric cancer in Japan and the fact that more than half of Japanese gastric cancer cases are diagnosed at an early stage. Very recently, several EMR techniques have become increasingly accepted and regularly used in Western countries. Although these minimally invasive techniques are safe, convenient, and efficacious, they are unsuitable for large lesions in particular. Difficulty in correctly assessing the depth of tumor invasion and an increase in local recurrence when standard EMR procedures are used have been reported in cases of large lesions, because such lesions are often resected piecemeal owing to the technical limitations of standard EMR. A new development in therapeutic endoscopy, called endoscopic submucosal dissection (ESD), allows the direct dissection of the submucosa, and large lesions can be resected en bloc. ESD is not limited by resection size and is expected to replace surgical resection. However, it is still associated with a higher incidence of complications than standard EMR procedures and requires a high level of endoscopic skill. The endoscopic indications, techniques, and management of complications of ESD for early gastric cancer for properly carrying out established therapeutic endoscopy are described.     

CURRENT TECHNIQUES AND DEVICES FOR SAFE AND CONVENIENT ENDOSCOPIC SUBMUCOSAL DISSECTION (ESD) AND KOREAN EXPERIENCE OF ESD

Conventional endoscopic mucosal resection (EMR) technique has limitations in its capacity of achieving en bloc resection and, for lesions greater than 20 mm, removal in a piecemeal resection is often required. This leads to uncertainty as to whether or not the lesion has been completely removed and to an increase in local recurrence. To overcome this limitation, a new technique using specifically designed cutting devices, termed endoscopic submucosal dissection (ESD) has been developed. The present article discuss the current indication, new diagnostic, cutting and hemostatic devices and long‐term outcomes of EMR and ESD in early gastric cancer in Korea.     

CHARACTERISTICS AND ROLE OF ENDOSCOPIC MUCOSAL RESECTION USING CAP‐FITTED PANENDOSCOPE FOR EARLY GASTRIC CANCER

Background: It is accepted in Japan and in the gastric cancer treatment guidelines that small gastric mucosal cancers without lymph node metastasis can be curatively treated by endoscopic mucosal resection (EMR). Various techniques of EMR for early gastric cancer have been reported, and in the present study, the results of EMR using cap‐fitted panendoscope (EMRC) for early gastric neoplastic lesions are examined, and the characteristics and the role of EMRC procedure are discussed. Methods: From August 1992 to March 2003, 181 gastric neoplastic lesions in 155 patients were treated by EMRC at the Department of Surgery, Esophagogastric Division, Tokyo Medical and Dental University. The frequency of residue and the cause of residue following EMRC for 181 gastric neoplastic lesions were examined. Five‐year survival rates were calculated and compared according to the 49 patients who underwent en bloc resection and the 49 patients who underwent planned fractionated resection by EMRC for early gastric cancer. Results: There was residue in nine (5%) of 181 lesions treated by EMRC. Residues from four elevated lesions resulted from muscular resection and insufficient additional resection; residues from five depressed lesions resulted from incorrect diagnosis of the spread of the lesions prior to resection and insufficient additional resection. In the EMRC patients, the survival rates for 49 patients treated by en bloc resection (93%) and 49 patients by planned fractionated resection (91%) were not significantly different. Conclusion: The EMRC technique, that is en bloc and planned fractionated resection by EMRC procedure, has an important role as an easy and curative EMR method for almost all of the indicated early gastric cancers by the gastric cancer treatment guidelines with no limitations from the lesion sites.     

ENDOSCOPIC MUCOSAL RESECTION AND SUBMUCOSAL DISSECTION METHOD FOR LARGE COLORECTAL TUMORS

The goal of endoscopic mucosal resection (EMR) is to allow the endoscopist to obtain tissue or resect lesions not previously amenable to standard biopsy or excisional techniques and to remove malignant lesions without open surgery. In this article, we describe the results of conventional EMR and EMR using an insulation‐tipped (IT) electrosurgical knife (submucosal dissection method) for large colorectal mucosal neoplasms and discuss the problems and future prospects of these procedures. At present, conventional EMR is much more feasible than EMR using IT‐knife from the perspectives of time, money, complication, and organ preservation. However, larger lesions tend to be resected in a piecemeal fashion; and it is difficult to confirm whether EMR has been complete. For accurate histopathological assessment of the resected specimen en bloc EMR is desirable although further experience is needed to establish its safety and efficacy. Further improvements of in EMR with special knife techniques are required to simply and safely remove large colorectal neoplasms.     

ENDOSCOPIC SUBMUCOSAL DISSECTION FOR RECURRENT GASTRIC TUMORS

Endoscopic resection has been accepted as the standard treatment for intramucosal gastric tumors of differentiated type. However, the indication was limited to small tumors to achieve en bloc resection and prevent local recurrence in cases of conventional endoscopic mucosal resection (EMR) such as the strip biopsy and the cap technique. To avoid multi‐fragmental resection, we have developed endoscopic submucosal dissection (ESD) as a new endoscopic resection technique. ESD is a remarkable technique, because we make it possible to remove the lesions en bloc regardless of size, shape, coexisting ulcer, and location. However, it is difficult or impossible to resect recurrent tumors en bloc in conventional EMR owing to hard fibrosis, and some patients need laparotomy. Using ESD, we can dissect the submucosal layer as we directly look at the submucosa, and remove the lesion safely and reliably even in cases of hard fibrosis. The key to treatment of recurrent tumors in ESD are as follows: (i) using enough submucosal injection solution (we use a mixture of Glyceol and 1% 1900 kDa hyaluronic acid preparation); (ii) incising the mucosa without fibrosis; (iii) understanding characteristics of various cutting devices, and changing other devices in difficult situations. In these ways we can remove the majority of the recurrent tumors en bloc. Hence, we consider that ESD is a very effective treatment which achieves excellent en bloc and complete resection rates and enables patients with intramucosal gastric tumors to a recurrent‐free survival even in recurrent tumors.     

Successful en bloc resection of a large superficial gastric cancer by using sodium hyaluronate and electrocautery incision forceps.

BACKGROUND: The advisability of endoscopic mucosal resection (EMR) for treatment of large superficial gastric cancers has been challenged. For more reliable en bloc resection, a new method of EMR was developed that uses a viscous substance, sodium hyaluronate, and two newly designed devices. METHODS: A large superficial gastric cancer was treated with this new EMR technique. Sodium hyaluronate was injected into the submucosa and mucosal incisions were made with a needle-knife. The newly developed incision forceps and flat-ended transparent hood were used for submucosal incisions. RESULTS: The large cancer was successfully resected endoscopically as a single piece of mucosa 6 cm in diameter without complication. Histopathologic evaluation of the specimen confirmed that the resection was curative. CONCLUSIONS: EMR with sodium hyaluronate along with two new devices may be a reliable method for en bloc resection of large superficial gastric lesions.     

IS IT DIFFICULT FOR ENDOSCOPISTS WHO HAVE DONE CONVENTIONAL ENDOSCOPIC MUCOSAL RESECTION TO PERFORM SUBMUCOSAL DISSECTION?

Submucosal resection is a very useful method of endoscopic mucosal resection (EMR) for en bloc resection. We began using this method in March 2003 and have resected lesions in 16 patients with gastric cancer. We describe the procedure times and complications associated with submucosal resection from a beginner's point of view. Our first five patients experienced bleeding and perforation. With the aid of a range of instruments and the advice of expert endoscopists, our complication rate became very low and the procedure time much shorter. Endoscopists who seek to perform submucosal dissections easily and safely should avail themselves of training and education from experts in the method. A program for training endoscopists in submucosal dissection is essential.     

Risk factors for incomplete resection and complications in endoscopic mucosal resection for lateral spreading tumors

Aim: Lateral spreading tumors (LST) are relatively large flat lesions with diameters exceeding 10 mm in length. Endoscopic mucosal resection (EMR) is a commonly used technique for removing LST. We aimed to evaluate the risk factors for incomplete resection and complications of EMR for LST. Method: Between January 2004 and December 2010, 497 patients who underwent EMR for LST were retrospectively reviewed. Risk factors for endoscopic and histopathological complete resection, complications, and clinical outcomes were investigated. Results: Risks for incomplete resection by piecemeal resection and en bloc resection of a lesion ≥30 mm were higher than for en bloc resection of a lesion <30 mm (OR = 2.688, CI 1.036–6.993; OR = 4.982, CI 1.894–13.101). Risks of post‐EMR bleeding for piecemeal resection and en bloc resection for a lesion ≥40 mm were higher than for en bloc resection of a lesion < 40 mm (OR = 15.231, CI 1.816–127.744; OR = 43.043, CI 4.306–430.314). Conclusion: We found risk factors of EMR for LST and tentatively suggest a protocol for EMR adapted to the size of LST and resection methods. (i) Following piecemeal resection and en bloc resection for LST ≥ 40 mm, hospitalize patients for 36 h and note risk for incomplete resection and delayed bleeding. (ii) After en bloc resection for 40 mm > LST ≥ 30 mm, hospitalize patients for 12 h and note risk for incomplete resection. (iii) Following en bloc resection for LST < 30 mm, hospitalize the patient for 12 h and expect complete resection.     

Matched case-control study comparing endoscopic submucosal dissection and endoscopic mucosal resection for colorectal tumors

Background and Aim: For large colorectal tumors, the en bloc resection rate achieved by endoscopic mucosal resection (EMR) is insufficient, and this leads to a high rate of local recurrence. As endoscopic submucosal dissection (ESD) has been reported to achieve a higher rate of en bloc resection and a lower rate of local recurrence in the short‐term, it is expected to overcome the limitations of EMR. We conducted a matched case‐control study between ESD and EMR to clarify the effectiveness of ESD for colorectal tumors. Methods: Between April 2005 and February 2009, a total of 28 colorectal tumors in 28 patients were resected by ESD and were followed up by colonoscopy at least once. As a control group, 56 EMR cases from our prospectively completed database were matched. En bloc resection, complication and recurrence rates were compared between the two groups. Results: The mean sizes of the lesions were 27.1 mm in the ESD group and 25.0 mm in the EMR group. The en bloc resection rate was significantly higher in the ESD group (92.9% vs 37.5% with ESD vs EMR), and the rate of perforation was also significantly higher (10.7% vs 0%). All cases of perforation were managed conservatively. No recurrence was observed in the ESD group, whereas local recurrences were detected in 12 EMR cases (21.4%). Eleven of the 12 recurrences (91.7%) were managed endoscopically, and one required surgical resection. Conclusions: Endoscopic submucosal dissection is a promising technique for the treatment of colorectal tumors, giving an excellent outcome in comparison with EMR.     

THE TECHNICAL FUNDAMENTALS OF ENDOSCOPIC MUCOSAL RESECTION IN THE COLON: OUR METHOD

Endoscopic mucosal resection (EMR) is the technique used to resect flat or depressed tumors or larger tumors such as laterally spreading tumors with marginal normal mucosa. Recently, endoscopic mucosal dissection technique has been rapidly accepted, mainly in early gastric cancer in Japan. We need to have firm knowledge of EMR technique in the colon for recovery as we advance this new technique. We describe our conventional EMR method practically. EMR should be performed to locate the target lesion at down side to perform sure EMR. The ideal shape of upheaval by saline injection is hemisphere. The needle sheath and snare should be taken out a little of the endoscopy to manipulate firmly. Another technique of secure EMR is the snare manipulation. We prefer that the shape of the snare is circular and the snare is hard. It is important while trapping to press the target lesion with both the whole snare circle and the end of the sheath. With these fundamental procedures we could resect the target lesions at will.     

SYNCHRONOUS MULTICENTRIC SIGNET‐RING CELL CARCINOMA OF THE STOMACH

A case of simultaneous multicentric signet‐ring cell carcinoma (SRC) of stomach is presented. Initially, an early gastric cancer (IIc) was diagnosed and this was cured with distal gastrectomy. Thirty‐eight months after the operation, follow‐up endoscopy revealed a tiny mucosal discoloration lesion, which was diagnosed as a minute SRC focus with biopsy. This was successfully treated with endoscopic mucosal resection (EMR). Nine months later, gastroscopy discovered another small mucosal lesion and it was again diagnosed as a tiny SRC lesion, which was also successfully treated with EMR. After a further 2 months, endoscopy showed three small mucosal lesions (discoloration) similar to previous lesions, two of which proved to be SRC with biopsy. As these lesions distributed widely over the remnant stomach, total gastrectomy of the residual stomach was performed. Pathological examination demonstrated a total of 22 simultaneous multifocal SRC lesions, which were all very small mucosal cancer. These cancers, including previously EMR‐treated ones, seemed to develop in a multicentric manner, as they were diagnosed within 11 months. This case also indicated that even subtle endoscopic findings should vigorously be sought and, if in doubt, be biopsied in order to locate gastric cancer early enough for minimal invasive curative treatment to be feasible.     

早期胃癌内镜治愈性切除的影响因素

目的分析影响早期胃癌内镜治愈性切除的危险因素,提高内镜治愈性切除早期胃癌的可能性。方法收集2008年10月至2013年3月行内镜切除治疗的早期胃癌（包括高级别上皮内瘤变）患者的临床资料;分析性别、年龄、病灶位置、病灶直径、病灶内镜形态学分型及伴有溃疡形成6个因素对内镜切除术（ER）整块切除及治愈性切除的影响;同时分析非治愈性切除的主要原因。结果纳入早期胃癌共94例包含94个病灶,其中高级别上皮内瘤变病灶20个,黏膜内癌病灶70个,黏膜下浅层浸润癌（距黏膜肌层500斗m以内）病灶4个。其中5个病灶经EMR切除,89个病灶经ESD切除。ER整块切除率为95．7％（90／94）,治愈性切除率为79．8％（75／94）。直径〉3．0cm的病灶治愈性切除率显著低于直径≤2．0em的病灶（P=0．022,OR=0．108,95％C1：0．016—0．721）,伴有溃疡形成的病灶治愈性切除率显著低于不伴有溃疡形成的病灶（P=0．047,OR=0．149,95％CI：0．023～0．971）。非治愈性切除的主要原因是侧缘肿瘤细胞的残留。结论病灶直径〉3．0cm、伴有溃疡形成是影响早期胃癌ER治愈性切除的危险因素。     

Beyond the snare: technically accessible large en bloc colonic resection in the West: an animal study

Background: Endoscopic submucosal dissection (ESD) and circumferential submucosal incision endoscopic mucosal resection (CSI‐EMR) are techniques for en bloc excision of large sessile colonic lesions. Our aims were to compare the efficacy, safety and learning curve of colonic hybrid knife (HK) ESD versus CSI‐EMR for en bloc excision of 50 mm diameter hemi‐circumferential artificial lesions in a porcine model. Patients and Methods: Two separate 50 mm diameter areas of normal recto‐sigmoid mucosa were marked out in each of ten pigs. One was excised with HK‐ESD using succinylated gelatin (SG) submucosal injection. The other was isolated with CSI with the Insulated Tip Knife 2 followed by SG submucosal injection then EMR with a large snare. Euthanasia and colectomy was performed at 72 h followed by blinded histopathology assessment. Results: En bloc excision rates were: HK‐ESD 100% versus CSI‐EMR 20% (P = 0.008). The mean number of resections per lesion was HK‐ESD 1 versus CSI‐EMR 3 (P = 0.001). The mean dimensions of the largest specimen per technique were HK‐ESD 63 × 54 mm versus CSI‐EMR 49 × 41 mm (P = 0.005). Procedure duration mean was HK‐ESD 54 min versus CSI‐EMR 22 min (P < 0.001). When procedure duration was adjusted for the size of the resected en bloc specimen, a statistically significant and accelerated learning effect was noted for HK‐ESD (r = ?0.83, P = 0.003). There were no perforations and no significant bleeding. Conclusions: HK‐ESD with SG submucosal injection is superior to CSI‐EMR for en bloc excision of 50 mm diameter lesions in a porcine model. The technique is rapidly learnt. This novel approach may lower the barrier to colonic ESD for Western endoscopists.     

Success rate of curative endoscopic mucosal resection with circumferential mucosal incision assisted by submucosal injection of sodium hyaluronate

BACKGROUND: Circumferential mucosal incision around a lesion is effective for reliable endoscopic mucosal resection. However, mucosal incision with a needle knife is difficult, even with submucosal injection of normal saline solution. To make needle-knife incision easier and safer, sodium hyaluronate has been used rather than normal saline solution. The aim of this study was to evaluate the clinical outcome of endoscopic mucosal resection with circumferential mucosal incision assisted by submucosal injection of sodium hyaluronate. METHODS: For 70 gastric lesions treated by submucosal injection of sodium hyaluronate, the size of the lesion and the resection specimen, the en bloc resection rate, complications, and local recurrence during follow-up were assessed. RESULTS: The mean size of the lesions and resection specimens were, respectively, 19.9 mm and 30.0 mm. The en bloc resection rates were 89% (42/47) for lesions up to 20 mm in diameter and 48% (11/23) for those greater than 20 mm (1-20 mm vs. >20 mm, p = 0.0004). Three patients underwent surgery because of invasive cancer in the EMR specimen. During follow-up (median 14 months, range 3-38 months), 2 recurrent lesions were found. No major complication occurred. CONCLUSIONS: Submucosal injection of sodium hyaluronate is a reliable method with a high success rate for en bloc resection of lesions up to 20 mm in diameter. Mucosal incision with a needle knife can be performed safely with submucosal injection of sodium hyaluronate.     

SUCCESSFUL ENDOSCOPIC SUBMUCOSAL DISSECTION FOR MUCOSAL CANCER OF THE DUODENUM

We report a case of mucosal duodenal cancer in a 62‐year‐old woman, which was successfully removed en bloc by endoscopic submucosal dissection (ESD). The patient underwent an upper gastrointestinal endoscopy at our hospital, which revealed an elevated flat mucosal lesion (type IIa) measuring 10 mm in diameter in the second portion of the duodenum. Histopathological examination of a biopsy specimen revealed features suggestive of a tubulovillous adenoma with severe atypia. As the findings suggested that the lesion had an adenocarcinoma component but was confined to the mucosal layer, we decided to carry out ESD and successfully removed the tumor in one piece. The resected tumor was 20 × 15 mm in size. Histopathological examination revealed that the lesion was a well‐differentiated mucosal adenocarcinoma with no lymphovascular invasion. Mucosal duodenal cancer is extremely rare, and ESD of a lesion in the duodenum requires a high level of skill. To the best of our knowledge, this case is the first report of successful ESD carried out in a case of mucosal duodenal cancer.     

FACTORS RELATED TO LATERAL MARGIN POSITIVITY FOR CANCER IN GASTRIC SPECIMENS OF ENDOSCOPIC SUBMUCOSAL DISSECTION

Background: With the widespread use of endoscopic submucosal dissection (ESD), more large early gastric cancers (EGC) have become candidates for endoscopic resection. A precise diagnosis of the extent of cancer is indispensable to obtain R0 resection. The aim of the present study was to clarify the factors related to lateral margin positivity for cancer in specimens resected by ESD for EGC. Methods: Among 1549 EGC treated by ESD during September 2002 to December 2008, lesions that were resected in an en‐bloc fashion and resulted in a pathological diagnosis of lateral margin positive (LM+) for cancer, were extracted. The reason for LM+ and pathological characteristics of the lesions were studied and compared to lesions successfully resected with margins negative for cancer. Results: There were three types of lesion that resulted in LM+ resection: lesions with a flat spreading area, lesions with an unexpected nearby lesion, and lesions with lateral extension beneath a non‐cancerous mucosa. Compared to lesions resected with margins negative for cancer, diameter of the tumor, recurrent‐type cancer, submucosal cancer, and undifferentiated‐type cancer were factors significantly related to LM+ resection. Conclusion: Other than misdiagnosing a small portion of cancer extension, lateral margin positivity for cancer by ESD could result from a neighboring lesion and an unexpected lateral submucosal cancer extension. To avoid LM+ resection of EGC by ESD, one should be careful of unexpected lateral extension and simultaneous multi‐lesions.     

Treatment strategy for laterally spreading tumors in Japan: Before and after the introduction of endoscopic submucosal dissection

Background and Aims:  Laterally spreading tumors (LST) in the colorectum are considered good candidates for endoscopic resection (ER). Because LST-non-granular (NG) tumors show multifocal invasion into the submucosal layer, en bloc resection is necessary for adequate histopathological evaluation. Therefore, surgical resection has been recommended when a lesion is suspected to be an invasive cancer and too large to resect en bloc. The aim of the present study was to evaluate whether the introduction of colorectal ESD, which was developed for en bloc resection of early gastric cancers, could improve the en bloc resection rate of large LST-NG-type tumors and reduce the surgical resection rate.
Methods:  Between January 1999 and December 2005, a total of 166 LST-NG-type tumors measuring ≥ 20 mm in 161 patients were included in this study. The en bloc resection rate and the surgical resection rate were historically compared between two periods, before and after the introduction of ESD.
Results:  The en bloc resection rate for ER lesions was significantly higher in the latter period (35.0% [14/40] vs 76.5% [75/98]; P  < 0.001), and the rate of surgery for adenomas and intramucosal or sm minute cancers was significantly lower in the latter period (20.0% [10/50] vs 1.1% [1/89]; P  < 0.001).
Conclusions:  The introduction of colonic ESD was able to change our treatment strategy for LST, improving the en bloc resection rate and reducing the surgical resection rate.