all colorectal lesions were 80% and 90% (p� 0.02) respectively. Theaccuracies for differentiation of SSAs versus HPs were 72% and 88%(p�0.01). See table 2 for corresponding sensitivities and specificities.Conclusion: This study showed that “cloud like surface”, “irregular shape” and“dark spots inside the crypts” are 3 independent predicting endoscopicfeatures of SSAs. Combining these 3 features in a predictive algorithmresulted in an accuracy for differentiation of SSAs of 80% using HRE, and asignificantly higher accuracy of 90% using NBI. Future studies are needed toassess whether this algorithm can be used for differentiation of SSAs duringreal time colonoscopy.

Table 1. Standardized form of potential endoscopic features of SSAs

cloud like surfaceirregular shapeindistinct bordersdark spots inside the cryptsno tiny microvessels on surfaceKudo pit pattern I/II or \“II SSA”\normal vascular pattern intensity (VPI)size

Table 2. Sensitivity, specificity and accuracy of HRE and NBI

SSAs vs. all colorectalpolyps SSAs vs. HPs

HRE NBIP

value HRE NBIP

value

Sensitivity 67% 87% 0.03 67% 87% 0.03Specificity 87% 92% 0.13 77% 90% 0.22Accuracy 80% 90% 0.02 72% 88% 0.01

Su1415Risk Factors of Vertical Incomplete Resection in EndoscopicSubmucosal Dissection (ESD) as a Total Excisional Biopsy forColorectal Submucosal Invasive CancerShunichiro Ozawa*1, Shinji Tanaka1, Nana Nakayama2,Motomi Terasaki2, Koichi Nakadoi2, Sayaka Takata2, Hiroyuki Kanao1,Shiro Oka1, Shigeto Yoshida1, Kazuaki Chayama2

1Department of Endoscopy, Hiroshima University Hospital, Hiroshima-shi,Hiroshima-ken, Japan; 2Department of Gastroenterological andMetabolism, Hiroshima University Hospital, Hiroshima-shi,Hiroshima-ken, JapanEndoscopic submucosal dissection (ESD) for colorectal tumor is both a minimallyinvasive treatment and a total excisional biopsy, irrespective of the size of lesion.Using ESD specimen, we can assess lymphovascular invasion, budding andhistological type of the deepest invasive site, and the information from this playsa major role in selection of therapeutic strategy for submucosal invasive cancer(SMca). The Aim of this study is to clarify risk factors of vertical incompleteresection in ESD as a total excisional biopsy for colorectal submucosal invasivecancer. Materials and Methods: From June 2003 through October 2011, 395 caseswith colorectal tumor were treated by ESD at Hiroshima University Hospital. Ofthem, we evaluated 74 cases of SMca. We examined the preoperative factors(number of ESD cases, location of tumor, tumor size, growth pattern, invasivedepth diagnosis), intraoperative factors (hemorrhage, degree of submucosalfibrosis, the presence or absence of combination use of snaring, success orfailure of en bloc resection) and pathologic factors (main histologic type,histologic type of the deepest invasive site, submucosal invasion depth,infiltration pattern, submucosal fibrosis) as predictive factors of positive verticalmargin (VM�). Results: The average diameter of the tumor was 33.2�17.6mm(mean�SD), the percentage of en bloc resection was 95.9%, the rate ofperforation was 1.4%. The number of VM� cases was seven (9.5%), theincidence of cases showing VM� was significantly higher in cases that invasiondepth were deeper than 2000 �m. In these 7 cases, submucosal fibrosis wasdetected in 6 cases. Moreover, the histologic type at the deepest invasive sitewas poor differentiation in 6 cases, additionally, though 2 cases whose invasiondepth were less than 2000 �m showed poor differentiation at the deepestinvasive site. Among the cases examined by endoscopic ultrasonography prior toESD, 4 cases were diagnosed as deep submucosal invasion, and one case wasVM� of these 4 cases. Conclusion: Submucosal fibrosis or poor differentiation atthe deepest invasive site was a high risk for VM� in colorectal ESD for caseswith submucosal deep invasion.

Su1416Hyaluronic Acid-Assisted Snare Tip Cutting EMR (HSTC-EMR) inTreating Colorectal Tumors is Clinically UsefulMitsunori Yasuda*1,2, Satoshi Kokura2, Yuji Naito2,Toshikazu Yoshikawa2

1Gastroenterology and Hepatology, Kobe Social Insurance CentralHospital, Kobe, Japan; 2Gastroenterology and Hepatplogy, KyotoPrefectural University of Medicine, Kyoro, JapanBackground and Aims: When performing endoscopic resection of colorectaltumors, particularly adenomas and intra-adenomatous cancers, endoscopistsgenerally perform either a polypectomy with an ordinary snare or use a snaringto perform Endoscopic Mucosal Resection (EMR) after administering asubmucosal local injection. The important thing is to make sure that a negativelateral resection margin is achieved. This requires expert advanced snaringtechnique with awareness of resection margins. However, when the snare isconstricted, it may slip and slide on the surface of the tumor, resulting in apositive lateral resection margin, especially in cases in which the tumor beingoperated on is flat. One sure method of en bloc resection is the recentlydeveloped method of Endoscopic Submucosal Dissection (ESD), but thisprocedure is technically difficult, expensive, and time-consuming, while theincidence of complications is relatively high. Seeking a method that would besimple, low in cost, reliable, and ensure negative lateral resection margins, wedeveloped an EMR method that secures a suitable lateral margin by cuttingaround the periphery of the tumor with the tip of a polypectomy snare afterlocal injection of hyaluronic acid, which excels in maintaining tissue elevation.We compared this method with conventional EMR in terms of efficacy andsafety. Subjects and Methods: The patients studied were 306 colorectal tumorpatients for whom en bloc endoscopic resection was indicated between April2008 and Nov. 2011. Among these patients, 258 underwent conventional EMR(Con-EMR) performed with a snare ring after local injection of saline, while 48underwent Hyaluronic acid-assisted Snare Tip Cutting EMR (HSTC-EMR). Therewere no significant differences between the resection targets in terms ofmacroscopicity, size, ratio of adenoma to cancer, or other relevant factors. HSTC-EMR was performed according to the following procedure: (1) administration ofa local injection of hyaluronic acid with added indigo carmine; (2) extension ofthe tip of a polypectomy snare (Snare Master, Olympus) only about 1mm fromthe sheath to cut around the periphery of the tumor to the extent that the snaredoes not slip, while maintaining the margin; and (3) performance of EMR.Results: Con-EMR had a negative lateral margin rate of 78% (201/258) comparedto 94% (45/48) for HSTC-EMR, and HSTC-EMR was significantly superior to Con-EMR in terms of en bloc complete resection rate. No serious complications wereobserved with either method. Conclusions: Among endoscopic resectionmethods for colorectal tumors, HSTC-EMR is a clinically useful method that issimple, safe, and relatively low in cost.

Su1417Outcomes of Colorectal Endoscopic Submucosal Dissection andRisk Factors for Technical Difficulty: A Prospective Multi-CenterStudy on Endoscopic Treatment of Large Early ColorectalNeoplasmsYoji Takeuchi*1,2, Yutaka Saito1,3, Hiroyasu Iishi1,2, Hiroaki Ikematsu1,4,Shin-Ei Kudo1,5, Yasushi Sano1,6, Takashi Hisabe1,7, Naohisa Yahagi1,8,Yusuke Saitoh1,9, Masahiro Igarashi1,10, Kiyonori Kobayashi1,11,Hiro-O Yamano1,12, Seiji Shimizu1,13, Osamu Tsuruta1,14, Yuji Inoue1,15,Toshiaki Watanabe1,16, Hisashi Nakamura1,17, Takahiro Fujii1,18,Hideki Ishikawa1,19, Kenichi Sugihara1,20, Shinji Tanaka1,21

1Colorectal Endoscopic Resection Standardization ImplementationWorking Group, Japanese Society for Cancer of the Colon and Rectum,Tokyo, Japan; 2Department of Gastrointestinal Oncology, OsakaMedical Center for Cancer and Cardiovascular Disease, Osaka, Japan;3Endoscopy Division, National Cancer Center Hospital, Tokyo, Japan;4Division of Digestive Endoscopy and Gastrointestinal Oncology,National Cancer Center Hospital East, Kashiwa, Japan; 5DigestiveDisease Center, Showa University Northern Yokohama Hospital,Yokohama, Japan; 6Gastrointestinal Center, Sano Hospital, Kobe,Japan; 7Department of Gastroenterology, Fukuoka University ChikushiHospital, Chikushino, Japan; 8Department of Gastroenterology,Toranomon Hospital, Tokyo, Japan; 9Digestive Disease Center,Asahikawa City Hospital, Asahikawa, Japan; 10Department ofEndoscopy, Cancer Institute Hospital of Japanese Foundation forCancer Research, Tokyo, Japan; 11Department of Gastroenterology,Kitasato University East Hospital, Sagamihara, Japan; 12Department ofGastroenterology, Akita Red Cross Hospital, Akita, Japan;13Department of Gastroenterology,

Abstracts

www.giejournal.org Volume 75, No. 4S : 2012 GASTROINTESTINAL ENDOSCOPY AB324

Osaka General Hospital of West Japan Railway Company, Osaka,Japan; 14Division of Gastroenterology, Kurume University School ofMedicine, Kurume, Japan; 15Department of GastroenterologicalSurgery, Tokyo Women’s Medical University, Tokyo, Japan;16Department of Surgery, Teikyo University, Tokyo, Japan;17Department of Gastroenterology, Chofu Surgical Clinic, Cho-fu,Japan; 18TF Clinic, Tokyo, Japan; 19Department of Molecular-TargetingCancer Prevention, Kyoto Prefectural University of Medicine, Kyoto,Japan; 20Surgical Oncology, Tokyo Medical & Dental University, Tokyo,Japan; 21Department of Endoscopy, Hiroshima University, Hiroshima,JapanIntroduction: Endoscopic submucosal dissection (ESD) is a promising techniqueproviding high en bloc resection rate for precise histological assessment andelimination of tumor residue. However, ESD for colorectal neoplasm (CRN) hastechnical difficulty in relation with the risks of procedure failure, long operation timeand perforation. Objectives: To investigate the technical outcomes and the riskfactors for “technical difficulties (procedure failure, operation time longer than 2 hr.or perforation)” of ESD for CRN. Methods: The Japanese Society for Cancer of theColon and Rectum (JSCCR) conducted a prospective multi-center observational studyof consecutive patients undergoing ESD for superficial CRN larger than 20mm in 15specialized institutions. Characteristics of the lesions and technical outcomes of ESDfor CRN were collected and analyzed. Multivariate logistic regression analysisidentified independent risk factors for “technical difficulties” of ESD for CRN.Results: From Oct. 2007 to Dec. 2010, 816 CRNs in 808 cases (Mean age, 67 y.o.;465 males; median tumor size, 35mm) underwent ESD attempting en bloc resection.101 (12%) ESDs were performed in less-experienced (�30 cases) institution and 285(35%) ESDs were performed by less-experienced (�11 years) endoscopists. 520(64%) lesions were located in the colon, 296 (36%) in the rectum. The lesionsincluded 459 (56%) of granular laterally spreading tumors (LSTs), 281 (34%) of non-granular LSTs, 58 (7%) of protruded lesions, 5 of recurrent lesions after endoscopicresection. Lifting by submucosal injection was poor in 208 (25%) cases. en blocresection were abandoned in 45 cases: then endoscopic procedure were totallydiscontinued in one case and piecemeal resection were performed in 44 cases.Therefore, en bloc resection rate was 94%. Median (IQR) operation time was 78 (50-120) minutes and the operation time in 240 cases (29%) was longer than 2 hr.Perforation was occurred in 17 (2%) cases. Two cases (0.2%) underwent emergentsurgery due to perforation and intra-operative bleeding. The histopathologicalexamination disclosed 264 (32%) adenomas, 549 (67%) carcinomas. 663 (81%)lesions were intra-mucosal lesions, 88 (11%) slightly (�1mm) invaded submucosal(SM) cancers and 62 (7%) deeply (�1mm) invaded SM cancers. Independent riskfactors for “technical difficulties” are shown in the Table. Conclusion: ESD for CRNshowed high en bloc resection rate with acceptable adverse events. Large lesions,the lesions with poor lifting by submucosal injection, or deeply invaded SM cancerwere the independent risk factors for technical difficulty of ESD for CRN. In case oflesions suspicious for such risk factors, ESD for CRN had better not to be applied inless-experienced institutions or by less-experienced endoscopists. Independent riskfactors for “technical difficulties (procedure failure, operation time longer than 2 hr.or perforation).”

OR 95% C.I. P value

Lesions performed ESD in less-experiencedinstitution

2.54 1.55–4.17 0.002

Lesions performed ESD by less-experienced(�11 year) endoscopist

2.17 1.53–3.07 �0.0001

Lesions larger than 30mm and smaller than40mm

2.24 1.37–3.74 0.0016

Lesions larger than 40mm 7.08 4.25–12.07 �0.0001Lesions with poor lifting by submucosalinjection

2.73 1.83–4.10 �0.0001

Lesions invaded SM deeply 1.94 1.06–3.54 0.03

OR, Odds ratio; C.I., Confidence Interval; SM, submucosal layer.

Su1418Comparison of Treatment Outcomes of Endoscopic Stenting forColonic Versus Extracolonic Malignant ObstructionJi Yeon Kim*, Sang Gyun Kim, Jong Pil IM, Joo Sung Kim,Hyun Chae JungInternal Medicine, Seoul National University Hospital, Seoul, Republicof KoreaBackground and Aims: Self-expandable metal stents (SEMS) have been used as abridging or palliative treatment for malignant colorectal obstruction. Colonicobstruction may also arise from advanced extracolonic malignancy, but outcomesof stent placement for extracolonic malignancy are unclear. This study wasperformed to compare the clinical success rates, complication rates of colorectalstenting and stent patency duration in patients with colorectal cancer versus

those with extracolonic malignancy. Materials and Methods: Patients whounderwent endoscopic placement with uncovered SEMS for a malignantcolorectal obstruction were enrolled at Seoul National University Hospital fromApril 2005 and August 2011. We retrospectively reviewed the pathologic,surgical, colonoscopic report, and medical records of 209 consecutive patients.Results: Colonic stentings were performed for colorectal cancer in 149 patientsand for extracolonic malignancy in 60 patients. Obstruction sites were rectum in53 patients (25.4%), rectosigmoid junction or sigmoid colon in 88 (42.1%),decending colon in 25 (12.0%), splenic flexure or transverse colon in 32 (15.3%),and hepatic flexure or ascending colon in 11 (5.3%). The causes of obstructionin extracolonic malignancy were advanced gastric cancer in 39 patients (65.0%) ,pancreatic cancer in 9 (15.0%), ovarian cancer in 3 (5.0%) and others in 9(15.0%). Clinical success rates were similar between the 2 groups (92.6% vs.86.7%, p�0.688) and there was no significant risk factor for unsuccessfulendoscopic stenting by multivariate analysis. Re-obstruction in palliativeendoscopic SEMS placement occurred in 16 patients (21.9%) with colorectalcancer and 18 patients (30.0%) with extracolonic malignancy (p�0.288). Therewas no difference in the rate of perforation between the 2 groups (4.1% vs.8.3%, p�0.467). In both groups, there were 2 deaths within 10 days afterstenting respectively, but there was no death directly related to endoscopicprocedure. Median stent patency duration were 193 � 42.38 days in patientswith colorectal cancer and 186 � 31.72 days in patients with extracolonicmalignancy (p�0.253). Stent patency duration was not affected by underlyingmalignancy, previous surgery or palliative chemotherapy. Conclusion:Endoscopic colonic stenting is highly effective and comparable for palliation ofobstruction in extracolonic malignancy as well as colorectal cancer in terms ofclinical success, complications and duration of patency.

Su1419Preprocedure Haemoglobin and Fecal Occult Blood Testing forOptimising Colonoscopy Rates in a Resource Limited Setting forDiagnosing Colonic MalignancyAmit K. Dutta*, Alagammai Pl, Sudipta D. Chowdhury, Ashok ChackoGastrointestinal Sciences, Christian Medical College and Hospital,Vellore, IndiaBackground: Colonoscopy is the most accurate test to diagnose colonicmalignancy. However, it is not freely available in all countries. We report asimple precolonoscopy algorithm to optimise the procedure rate and identify thegroup of patients where this test is strongly recommended from a country withlimited resources. Methods: Five hundred Patients above 50 years of age whounderwent colonoscopy for suspected colonic malignancy (altered bowel habit,abdominal discomfort, fatigue, etc.) in the absence of overt bleeding per rectumwere included retrospectively in this study. As a protocol, these patients alsounderwent fecal occult blood testing twice along with blood haemoglobin levelestimation prior to colonoscopy. Fecal occult blood (FOB) was testedqualitatively using chromogen (guaiac test) based method. The combined utilityof blood haemoglobin (normal�11g %) and fecal occult blood testing inidentifying or excluding patients with colonic malignancy was assessed. Thealgorithm was further validated in a cohort of 200 patients. Informed consentwas obtained before colonoscopy. Results: The mean age of the 500 patientsstudied was 58.6�6.7 years and 177 (35.4%) were females. A lesion thatcould potentially bleed was present in 185 of them (tumour, ulcer, polyp,vascular lesion, haemorrhoids, diverticula, etc.). These included 21 patientswith adenomatous polyp and 15 with malignancy. FOB was positive in 134(26.8%) patients and 196 (39.2%) patients had anemia. Overall, 254(50.8%)patients had either one or both of the above characteristics. The performanceof our algorithm (Figure 1) in detecting colonic lesions is shown in table 1.All the patients with colonic malignancy were correctly identified (sensitivity100%) and absence of anemia along with negative FOB excluded malignancyin all the subjects (NPV � 100%). Using this algorithm prompt colonoscopyfor detecting cancer would not be required in 49.2% patients. Alternatively,since these tests can be performed in the primary care setting, it would helpto identify the group of patients who should be referred for colonoscopy.The NPV for detecting malignancy or adenomatous polyp was 95.9%. WhenFOB testing alone was used as a determinant for colonoscopy, 3(20%)patients with malignancy were missed and sensitivity fell to 80%. Thealgorithm was further validated in a cohort of 200 patients. Eight of these hadcolonic malignancy and anemia and/or FOB positive was present in all ofthem which suggest that our model performed well in the validation cohort.Conclusions: A simple algorithm based on anemia and FOB test can optimise therates of colonoscopy for detecting malignancy and also help identify the groupof patients in whom colonoscopy is essential. This may be a useful tool incountries with limited resources where screening colonoscopy is not feasible.Performance characteristics of the proposed algorithm in identifying andexcluding colonic malignancy and other lesions.

Abstracts

AB325 GASTROINTESTINAL ENDOSCOPY Volume 75, No. 4S : 2012 www.giejournal.org