Margaret Burt

OWE-002 Significance of biopsies before large colorectal endoscopic resections and histopathological features of high risk lesions

Introduction Guidelines on endoscopic resection (ER) of colorectal superficial neoplastic lesions (CSNL) recommend against biopsy sampling but many are extensively sampled prior to referral, despite the deleterious effect on ER, to exclude adenocarcinoma or high grade dysplasia (HGD), reflecting a lack of understanding of the incidence and nature of adenocarcinoma or HGD within different morphological sub-types. It is therefore important to define the significance of HGD on biopsy samples and place this in the context of the histopathological characteristics of high risk lesions. Methods ERs of large (≥2 cm) CSNL were included. Sensitivity and specificity of HGD on biopsy and higher risk morphology (laterally spreading tumour (LST) non-granular/LST mixed nodular type/IIc component) for diagnosing covert invasive adenocarcinoma and confirmed HGD after ER were calculated and compared (Mcnemar’s test). In addition, 50 high risk lesions (containing HGD or invasive adenocarcinoma) were subjected to more detailed histopathological analysis. Results Results from prior biopsy sampling were available for 291 lesions (mean size 62.8 mm). Histopathology after ER revealed HGD in 85 (29%) and invasive adenocarcinoma in 26 (9%). Sensitivity and specificity of HGD on biopsy (n=60) for invasive adenocarcinoma were 50% (95% CI 32%–68%) and 82% (95%–CI 77%–86%), and for confirmed HGD after ER were 47% (95% CI 37%–57%) and 90% (95% CI 85%–94%) respectively. Sensitivity and specificity of high risk morphology (n=124) for HGD after ER were 71% (95% CI 60%–79%) and 69% (95% CI 62%75%) respectively. The sensitivity of high risk morphology was significantly higher than HGD on biopsy sampling (p=0.002). Detailed histopathological analysis of high risk lesions revealed invasive adenocarcinoma in 40% but a further 18% had non-invasive areas with cytological and architectural features indistinguishable from invasive adenocarcinoma. HGD was multifocal in 56%. The mean size of the focus of HGD was only 5.6 mm, and of adenocarcinoma was 11.0 mm. Mean lesion size was 53.6 mm. Conclusion Biopsy sampling of large CSNL has no value in excluding high risk lesions and morphology alone has higher sensitivity for high risk lesions. Histopathological analysis of high risk lesions reveals that areas of HGD or adenocarcinoma are very small relative to the lesion size and many contain non-invasive areas which would be cytologically indistinguishable from invasive adenocarcinoma on a biopsy. Despite this, biopsy sampling remains extremely common. Understanding of these findings and improved education regarding accurate lesion assessment may help reduce rates of inappropriate sampling.

PTH-044 Risk of stenosis and outcomes following endoscopic resection of large colorectal lesions involving more than 75% of the luminal circumference

Introduction Little is known about the risk of stenosis and outcomes following endoscopic resection of colorectal lesions which leave extensive mucosal defects. A limited number of studies suggest significant stenosis rates, although reported outcomes and suggested management are conflicting. We determined the risk of stenosis and outcomes of endoscopic resection leaving mucosal defects≥75% of the circumference. Method Patients who underwent endoscopic resection using endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD) and hybrid techniques of colorectal lesions≥2 cm were included. Patients were grouped according to circumferential extent of the mucosal defect. Surveillance colonoscopy was performed at 3 and 12 months. Clinicopathological characteristics and outcomes were compared between groups. Results 435 lesions≥2 cm were resected using EMR (n=342), ESD (n=45) or hybrid techniques (n=48). Circumferential extent of the mucosal defect was ≥75% in 41 patients. 8 were fully circumferential: 1 caecal lesion and the rest in the recto-sigmoid and rectum. 3 circumferential lesions contained deeply invasive adenocarcinoma and 1 benign lesion ultimately required surgery. 41 lesions with a mucosal defect ≥75% of the circumference had a mean size of 100.5 mm vs 49.0 mm for other lesions (p<0.001). These patients had significantly more complications (16.7% vs 4.7%, p<0.001), including a higher rate of perforation (8.3% vs 2.3%, p=0.02), although none required surgery, and a significantly higher rate of recurrence (44.8% vs 9.2%, p<0.001). 79% of patients without cancer were free from recurrence and had avoided surgery at last follow up compared to 97% with mucosal defects<75% (p<0.001). Stenosis occurred in 7 patients: 4 lesions extensively involving the rectum and recto-sigmoid and 2 lesions involving the sigmoid extending to the rectosigmoid. 1 of these involved a mucosal defect of only 50% of the circumference and 3 were fully circumferential. 1 patient had a symptomatic anorectal stenosis requiring dilatation under anaesthesia, 1 patient was asymptomatic but underwent early dilatation after the first surveillance endoscopy. The remaining patients were asymptomatic and managed expectantly. In all these latter cases spontaneous improvement in the stricture was noted at the subsequent surveillance colonoscopy. Conclusion The majority of patients with these extensive complex lesions can successfully be treated with endoscopic resection and avoid surgery. However, these patients have a significantly greater risk of complications and recurrence and should be managed in a tertiary institution. Although there is a significant risk of stenosis, it appears that most cases are asymptomatic and spontaneously improve with expectant management. Disclosure of Interest None Declared

PTH-042 Outcomes of endoscopic resection of recurrent colorectal lesions treated at a uk tertiary referral centre

Introduction Endoscopic resection of large colorectal lesions, especially by piecemeal EMR, carries a significant risk of recurrence. Although several series examine the outcomes and risk of recurrence following endoscopic resection, few focus on the outcomes of patients being treated for recurrence after initial expert resection, and these mostly focus on one technique to deal with recurrence. We evaluated the outcomes after recurrence of colorectal lesions after apparent successful endoscopic resection in a specialised UK tertiary institution employing a range of resection techniques. Method Consecutive patients who underwent endoscopic resection of colorectal lesions≥2 cm were included. All lesions were assessed with magnification chromoendoscopy supplemented by colonoscopic ultrasound in selected cases. A lesion specific approach was used to decide on resection technique. Outcomes were evaluated for patients treated for recurrent lesions. Results Of 396 colorectal lesions≥2 cm successfully resected at our institution, recurrence occurred in 50. 36% of these patients had already had a mean of 1.6 previous failed attempts at resection prior to referral to our institution, and 66% had had either a failed attempt at resection or extensive sampling involving ≥6 biopsies or tattoo placed under the lesion. 69% of patients were successfully treated with further endoscopic resection and avoided surgery. 27 patients had endoscopic resection of a recurrence larger than 20 mm, with a mean lesion size of 48.3+/-19.1 mm. Techniques used were EMR (n=16), ESD (n=2), Hybrid ESD and EMR (n=9). The remaining lesions<2 cm were resected using EMR. A mean of 1.4+/-0.75 procedures were required to achieve successful endoscopic treatment of recurrence. 24 patients who were ultimately successfully treated with endoscopic resection required a single further endoscopic resection after recurrence, 10 patients required 2 or more further resections. 8 patients required surgery, 4 as a result of developing invasive adenocarcinoma with the recurrence. There were no perforations as a result of endoscopic resection of recurrent lesions and only 1 patient was readmitted with post-procedural bleeding which was managed conservatively. Conclusion These data demonstrate the challenges of an advanced endoscopic resection service in much of western practice where patients with recurrent lesions represent a particularly complex cohort, most of whom have already had extensive prior manipulation or attempts at resection. Familiarity with a range of resection techniques and appropriate equipment is essential to successfully treat recurrent lesions in this group with endoscopic resection, which can be achieved in the majority of patients without significant complications. Disclosure of Interest None Declared

Multimodal Endoscopic Evaluation Guides Treatment Decisions for Early Rectal Cancers and Complex Rectal Neoplasms

Introduction There is wide variation in the treatment of early rectal cancers and complex rectal neoplasms. With increasing emphasis on minimally invasive techniques and organ preservation, we aimed to evaluate the utility of a standardised, structured and rational assessment of rectal tumours to inform decision making for patients referred to a tertiary unit specialising in early rectal cancer. Method Since 2012, our unit has employed a standard approach to the assessment of rectal lesions which includes multimodal endoscopic assessment of all lesions using white light, magnification chromoendoscopy and colonoscopic high frequency miniprobe ultrasound to inform treatment decisions. Patients can then be allowed a fully informed decision regarding treatment options, which include advanced endoscopic resection, minimally invasive transanal endoscopic microsurgery (TEMS) or laparoscopic segmental oncological resection, all of which are offered by our unit. Results 191 patients (mean age 71 years) with rectal tumours were referred to our unit for an assessment regarding suitability for local resection. Multimodal endoscopic evaluation assessed 128 lesions as benign and 63 as malignant. 125 lesions with a mean size of 70.9 mm were treated with endoscopic resection: 108 adenomas, 9 adenocarcinomas and 5 neurendocrine tumours. 92% were performed without general anaesthesia and 78% as day cases. There were 2 small perforations treated endoscopically with clips with no adverse sequelae. The recurrence rate was 10%, all managed endoscopically. At last surveillance 97% of patients were free from recurrence. None required a major resection. 37 patients underwent TEMS as curative treatment or for patients unfit for, or refusing major resection. Only 3 patients with benign neoplasms had TEMS. The few remaining patients were either directed to major surgical resection, palliative options or declined treatment. Conclusion A standardised rational approach employing multimodal endoscopic evaluation for assessing complex rectal neoplasms results in high rates of safe, effective organ preserving treatment with almost no patients with benign disease subjected to a surgical procedure. Disclosure of Interest None Declared

Colorectal endoscopic submucosal dissection: patient selection and special considerations

Endoscopic submucosal dissection (ESD) enables en bloc resection of large complex colorectal superficial neoplastic lesions, resulting in very low rates of local recurrence, high-quality pathologic specimens for accurate histopathologic diagnosis and potentially curative treatment of early adenocarcinoma without resorting to major surgical resection. The safety and efficacy of the technique, which was pioneered in the upper gastrointestinal tract, has been established by the consistently impressive outcomes from expert centers in Japan and some other eastern countries. However, ESD is challenging to perform in the colorectum and there is a significant risk of complications, particularly in the early stages of the learning curve. Early studies from western centers raised concerns about the high complication rates, and the impressive results from Japanese centers were not replicated. As a result, many western endoscopists are skeptical about the role of ESD and few centers have incorporated the technique into their practice. Nevertheless, although the distribution of expertise, referral centers and modes of practice may differ in Japan and western countries, ESD has an important role and can be safely and effectively incorporated into western practice. Key to achieving this is meticulous lesion assessment and selection, appropriate referral to centers with the necessary expertise and experience and application of the appropriate technique individualized to the patient. This review discusses the advantages, risks and benefits of ESD to treat colorectal lesions and the importance of preprocedure lesion assessment and in vivo diagnosis and outlines a pragmatic rationale for appropriate lesion selection as well as the patient, technical and institutional factors that should be considered.

PTH-008 Endoscopic Resection of Large Colorectal Polyps in A UK Tertiary Referral Unit

Introduction Whilst the extensive experience of endoscopic resection of large colorectal polyps in Japan has resulted in clear and consistent indications for various techniques depending on polyp size and morphology, practise in western Europe is less well defined. We report the results of a prospective series of endoscopic resections using a variety of techniques from one of only a few tertiary referral centres in the UK providing advanced interventional endoscopy. The patients in this series present some unique challenges, for example the high proportion of patients referred with deeply scarred lesions after previous failed attempts at resection, and the large mean polyp size. Methods A prospective series of colorectal endoscopic resections form a tertiary referral centre in the UK. Surveillance endoscopy was performed at 3 months and 12 months after resection. Results 363 polyps with a mean size of 56 mm were resected in 326 patients who had a mean age of 71 years: 309 by EMR, 38 by ESD and 16 by hybrid procedures involving ESD. The mean follow up was 12.2 months. Almost all patients were referred after their polyps were at least biopsied and 38% of polyps were deeply scarred from previous intervention. Despite this, adenoma recurrence occurred in only 9.7% of patients, 17% of which were diminutive. 6 patients with recurrence required surgery, 2 right hemicolectomies, 1 TEMS and 1 anterior resection and 2 declined surgery. 67% of patients with recurrence were treated successfully endoscopically with no further recurrence. Of those patients without invasive cancer at their first endoscopic resection, 95% were free from recurrence and had avoided surgery at last follow up. There was only one clinically significant perforation. 2 patients were admitted with post-procedure bleeding, 1 managed conservatively and 1 with endoscopic clips. Conclusion These data demonstrate the effectiveness of a tertiary interventional endoscopy unit in a western setting in treating large and complex colorectal polyps, with low recurrence rates and very few significant complications. In contrast to practise in the east, more education is required to prevent multiple attempted interventions before referral to a highly specialised unit. Disclosure of Interest None Declared

PTU-004 Safe and Effective Day Case Endoscopic Resection of Giant Colorectal Adenomas Greater than 8CM is Achievable in a Tertiary Referral Unit

Introduction There are few reports on the management of very large sessile colorectal polyps in western practice. Endoscopic resection of these lesions can be technically challenging and they have traditionally been subjected to surgical resection in western centres. Our aim was to determine the safety and effectiveness of endoscopic resection of giant colorectal polyps in a tertiary referral interventional endoscopy unit. Methods All lesions were assessed with magnification chromoendoscopy. Patients with colorectal polyps greater than or equal to 8 cm deemed suitable for endoscopic resection were included. Several techniques were employed including piecemeal endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD), and hybrid techniques involving EMR, ESD, transanal resection or transanal endoscopic microsurgery (TEMS). All patients underwent surveillance magnification chromoendoscopy at 3 and 12 months. Results 88 lesions greater than or equal to 8 cm were resected with a median size of 10 cm (range 8 cm-16cm). Mean age was 74 years. 49 lesions were in the rectum or rectosigmoid, 13 in the right colon and 27 in the descending and sigmoid colon. There were 6 tubular adenomas, 73 tubulovillous adenomas, 7 adenocarcinomas and 1 sessile serrated adenoma. The recurrence rate was 17%, 64% detected at the first surveillance endoscopy and 36% later recurrences. Of these, 2 patients required surgery in the form of TEMS and a right hemicolectomy, 1 died of unrelated causes, and the rest were managed with a repeat endoscopic resection and were free from recurrence at last surveillance. There were no clinically significant perforations. 3 perforations were closed with endoscopic clips and managed conservatively without complications. There were 2 unplanned admissions for bleeding which did not require further intervention. The recurrence and complication rate were significantly higher than for adenomas smaller than 8 cm. 72% were successfully completed as day cases. Of those patients without invasive cancer at their initial resection and alive at last follow up, 93% avoided surgery and were free from recurrence. Conclusion Successful endoscopic resection of giant colorectal adenomas is achievable in a western setting with a low risk of complications. In our series, none of 49 patients with rectal or rectosigmoid lesions, who would have traditionally required an anterior resection or abdominoperineal excision, required a major surgical resection. Almost all patients with benign polyps were successfully treated endoscopically and avoided surgery. Nonetheless, it is associated with a higher risk of complications and recurrence compared with lesions less than 8 cm and therefore should be considered in specialist units. Disclosure of Interest None Declared

PTU-005 Risk Factors for Recurrence Following Endoscopic Resection of Large Colorectal Polyps in a Western Population

Introduction Although consistent risk factors for recurrence after resection of colorectal polyps have been identified in eastern series, there are few data on risk factors in western practice which may have different patient populations, experience, referral patterns and employ different techniques. Our unit is one of only a few specialist interventional endoscopy units in the UK. As a result, many referred patients have very large polyps, deeply scarred lesions from previous attempts at resection and several had been deemed too frail to undergo treatment. We aimed to determine the risk factors for recurrence after endoscopic resection of large colorectal polyps in this population. Methods We analysed a series of endoscopic resections of large colorectal polyps. Several techniques were employed including EMR, ESD and hybrid techniques involving combinations of EMR, ESD, TEMS and transanal resection for particularly challenging polyps. Visible vessels were routinely coagulated. After resection, the area was scrutinised with magnification chromoendoscopy to check for residual polyp which was resected or ablated. Surveillance endoscopy was performed at 3 and 12 months. Results 363 polyps with a mean size of 56 mm were resected in 326 patients who had a mean age of 71 years: 309 by EMR, 38 by ESD and 16 by hybrid procedures. Mean follow up was 12.2 months. 38% of polyps were deeply scarred. Recurrence occurred in 9.7% of patients, 17% of which were diminutive. 66% of recurrences were apparent on the first surveillance endoscopy. Size > 30 mm, piecemeal resection, deeply scarred lesions and the use of argon plasma coagulation were associated with recurrence on univariate analysis. However, logistic regression revealed only piecemeal resection was independently associated with recurrence (OR 5.1, p = 0.03). Intraprocedural bleeding, old age, high grade dysplasia, rectal location and histological type were not significantly associated with recurrence. Furthermore, there were no significant differences in recurrence between lesions resected by ESD or EMR, or between lesions resected with traditional techniques and those using a hybrid of various endoscopic and minimally invasive surgical techniques. Conclusion In contrast to other series, we found only piecemeal resection to be associated with recurrence. We feel that the routine use of techniques such as post-resection assessment using magnification chromoendoscopy to detect residual polyp and routine coagulation of visible vessels helps to eliminate some of the risk factors for recurrence. These techniques may also account for the success of hybrid procedures to resect large polyps in difficult locations with similar recurrence rates, which are an invaluable option in some challenging cases. Disclosure of Interest None Declared