Table 2. Period of Local Recurrence

Months Adenoma (n�3) EGC (n�12)

3 2 96 1 19 112 1

Sa1570Factors Associated With Incomplete Endoscopic SubmucosalDissection for Early Gastric CancerHaruhisa Suzuki*, Ichiro ODA, Masau Sekiguchi, Satoru Nonaka,Shigetaka Yoshinaga, Yutaka SaitoEndoscopy Division, National Cancer Center Hospital, Tokyo, JapanBackground: Endoscopic submucosal dissection (ESD) is widely accepted fortreating early gastric cancer (EGC), but there still are cases of incompleteresection. Aim: To clarify factors associated with incomplete ESD for EGC.Method: A total of 2,268 patients with solitary EGC lesions at initial onsetunderwent ESD with curative intent at our hospital from 1999 to 2008. Weretrospectively assessed clinicopathological factors including age, gender, lesionlocation, size, depth of invasion, ulcerative change, major histological type(differentiated-type or undifferentiated-type) and procedure time by comparing171 incomplete ESD cases (7.5%) with 2,097 complete ESD cases (92.5%).Complete resection was defined as en-bloc resection with negative horizontal(HM) and vertical margins (VM). Of 171 incomplete ESD cases, a positive HMwas found in 91, a positive VM in 62 and both a positive HM and a positive VMin 18 of those cases. Results: Of the 109 cases with a positive HM, a positive HMdue to the misdiagnosis of a lesion extending pathologically beyond ESDmarking dots was found in 60 (55%). Using multivariate analysis, size �2cm(odds ratio [OR] 5.4; 95% confidence interval [CI], 3.0-9.9; P�0.0001),undifferentiated-type (OR 4.0; 95% CI, 1.8-8.9; P�0.0006), submucosal (SM)invasion (OR 2.0; 95% CI, 1.2-3.5; P�0.01) and location (upper and middle thirdsof the stomach) (OR 0.5; 95% CI, 0.3-1.0; P�0.04) were significantly associatedwith a positive HM due to such a misdiagnosis. The remaining 49 cases (45%)were HM positive because of technical ESD-related problems such as theburning effect on lesions, inadvertent intralesional incisions and piecemealresections. Based on multivariate analysis, procedure time �2 hours (OR 12.9;95% CI, 5.9-28.4; P�0.0001), location (upper and middle thirds) (OR 4.4; 95% CI,1.5-12.4; P�0.006) and size �2cm (OR 2.3; 95% CI, 1.2-4.4; P�0.01) weresignificantly associated with a positive HM attributable to any such technicalESD-related problems. In the 80 cases with a positive VM, 48 (60%) were VMpositive due to the misdiagnosis of a lesion involving SM deep invasion �500�mfrom the muscularis propria. Using multivariate analysis, size �2cm (OR 2.9; 95%CI, 1.6-5.3; P�0.0004) and location (upper and middle thirds) (OR 2.4; 95% CI,1.2-4.9; P�0.01) were significantly associated with a positive VM due to such amisdiagnosis. The remaining 32 patients (40%) were VM positive because oftechnical ESD-related problems. Procedure time �2 hours (OR 5.8; 95% CI, 2.6-12.8; P�0.0001) and ulcerative change (OR 2.9; 95% CI, 1.4-6.1; P�0.003) weresignificantly associated with a positive VM attributable to any such technicalESD-related problems based on multivariate analysis. Conclusion: Endoscopistsmust be aware of the factors associated with cases of incomplete ESD for EGC tofurther reduce the incidence of such cases.

Sa1571Risk Factors of Local Recurrence of Early Gastric Cancer AfterEndoscopic Submucosal Dissection: the Significance of MixedAdenocarcinoma in Histological TypeJae Pil Han*1, Su Jin Hong1, Hee Kyung Kim2, Moon Han Choi1,Jeong-Yeop Song1, Gene Hyun Bok1, Tae Hee Lee1, Bong MIN Ko1,Joo Young Cho1, Moon Sung Lee1

1Digestive Disease Center, Department of Internal Medicine, SoonChun Hyang University School of Medicine, Bucheon, Republic ofKorea; 2Department of Pathology, Soon Chun Hyang University Schoolof Medicine, Bucheon, Republic of KoreaBackgrounds and Aim: The histological type of gastric cancer is known as animportant factor of the disease progression and prognosis. Undifferentiatedgastric cancer has more aggressive behavior than differentiated type. However,prognosis of the early gastric cancer (EGC) containing a mixture of differentiatedand undifferentiated components is incompletely understood. Moreover, there isno consensus on indication for endoscopic treatment of EGC with mixedcomponents. This study aimed to assess the characteristics and prognosis ofmixed adenocarcinoma diagnosed as EGC after endoscopic submucosaldissection (ESD). Material And Methods: The EGCs histologically proven by ESDbetween May 2002 and September 2009 were enrolled in this study. These

tissues were reviewed by one pathologist and re-classified according to WHOclassification modified in 2010. The clinicopathological features, outcomes ofESD, and local recurrence rate were analyzed and compared among histologicaltypes. Results: A total 430 EGCs that met absolute or expanded criteria weretreated with ESD in 395 patients. They were re-classified as 363 (84.5%) tubular/papillary adenocarcinomas, 41 (9.5%) PCCs and 26 (6.0%) mixedadenocarcinomas according to modified WHO classification. Theclinicopathological characteristics among histologial type were shown in Table 1.Although en bloc resection rate was acceptable (92.3%) in mixedadenocarcinoma, complete resection rate was lower (53.8%) than in other types(P�0.01) from pathological result after ESD. Additional surgery was performed in4 patients with deep margin positivity or lymphovascular invasion. Of 8 patientswith lateral margin positivity, two were treated with endoscopic procedures and6 were followed up with endoscopic surveillance. During follow-up period(mean�SD, 47.3�27.5 month), local recurrence was occurred in five mixedadenocarcinoma (19.2%) including 3 with and 2 without lateral margin positivityin pathological result from ESD. In multivariate analysis, the independent riskfactors to predict local recurrence after ESD for EGC were incomplete resection(HR: 5.002, 95% CI 1.546-16.183, P�0.007) and mixed adenocarcinoma ofhistological types (HR: 7.039, 95% CI 1.798-27.552, P�0.01). Conclusions: Mixedadenocarcinoma according to modified WHO classification has higher possibilityof incomplete resection and local recurrence after ESD for EGC. Moreover, it hasmore lateral margin positivity in pathological result than other histological types,suggesting the discrepancy between endoscopic finding and pathological size.Therefore, careful examination before ESD and meticulous and long-termendoscopic surveillance after ESD might be needed in mixed adenocarcinoma.Index: Mixed adenocarcinoma, Early gastric cancer, WHO classification, Localrecurrence

Table 1. Comparison of clinicopathological characteristics among histologicaltypes of early gastric cancer

Mixedadenocarcinoma PCC

Tubular/papillaryadenocarcinoma

Pvalue

Number (%) 26 (6.0) 41 (9.5) 363 (84.5)Age (years, mean�SD) 55.3�15.8† 53.0�13.7† 62.2�10.3 0.000Gender, n (%) 0.258

Male 16 (61.5) 28 (68.3) 201 (55.4)Female 10 (38.5) 13 (31.7) 162 (44.6)

Forceps biopsy before ESD, n (%) 0 (0) 0 (0) 164 (45.2) 0.000Dysplasia Adenocarcinoma 21 (80.8) 32 (78.0) 199 (54.8)Signet ring cell carcinoma 5 (19.2) 9 (22.0) 0 (0)Histological type according to

previous classification, n (%)24 (92.3) 21 (51.2) 363 (100) 0.000

Adenocarcinoma Signet ring cellcarcinoma

2 (7.7) 20 (48.8) 0 (0)

Tumor size in pathological result(mm, mean�SD)

27.4�10.8‡ 19.3�9.2 16.6�10.4 0.000

En bloc resection, n (%) 24 (92.3) 26 (63.4) 328 (90.4) 0.000Complete resection, n (%) 14 (53.8) 32 (78.0) 319 (87.9) 0.000Incomplete resection, n (%) 12 (46.2) 9 (22.0) 44 (12.1) 0.000Lateral margin positivity 8 (30.8) 4 (9.8) 29 (8.0)Deep margin positivity 2 (7.7) 5 (12.2) 15 (4.1)Lymphovascular invasion 2 (7.7) 0 (0) 0 (0)Local recurrence 5 (19.2) 4 (9.8) 6 (1.7) 0.000

†Significant difference in age, compared with tubular/papillary adenocarcinoma using ANOVA‡Significant difference in size, compared with PCC and tubular/papillary adenocarcinoma usingANOVA

Sa1572Clinicopathological Factors of Multiple Lateral MarginInvolvement in Endoscopic Submucosal Dissection for EarlyGastric CancerJi Young Lee*1, Jun Hee Lee1, Jun Haeng Lee1, Kyoung-Mee Kim2,Ki Joo Kang1, Byung-Hoon MIN1, Jae J Kim1, Poong-Lyul Rhee1,Jong Chul Rhee1

1Devision of Gastroenterology, Department of Medicine, SamsungMedical Center, Seoul, Republic of Korea; 2Department of Pathology,Seoul, Republic of KoreaBackground: When the lateral margin of the resected specimen after endoscopicsubmucosal dissection (ESD) is involved by the tumor, additional treatment isusually required. In some patients, multiple lateral margins are involved.However, the factors related to the number of lateral margin involvement areunclear. Objective: To clarify the factors related to the multiplicity of lateralmargin involvement in specimen of ESD for early gastric cancer (EGC). Design:Retrospective study Setting: A tertiary center Patients: Between March 2004 toSeptember 2011, 71 patients (5.2%) with lateral margin positive specimen among1358 patients treated with ESD for EGC were included. Main Outcome

Abstracts

AB254 GASTROINTESTINAL ENDOSCOPY Volume 77, No. 5S : 2013 www.giejournal.org

Measurements: The demographic, endoscopic, and pathological features of singlelateral margin positive lesions (SLM� group) and multiple lateral margin positivelesions (MLM� group) were compared. Results: Forty-three lesions (60.6%) wereinvolved by just one lateral margin, and 28 lesions (39.4%) were involved by twoor more lateral margins. Extremely well-differentiated adenocarcinoma (EWDA)and histologic heterogeneity were more common in the MLM� group (p�0.043and p�0.070, respectively). In multivariate analysis, EWDA was the only onesignificant risk factor for multiple lateral margin involvement(OR 4.453[1.011-19.624, 95% CI], p � 0.048). As an additional treatment of positive lateral margin,surgery was done in 65% (46 cases) and additional ESD was performed in 20%(14 cases). After additional treatment, residual tumor was observed in 65%( 39 of60cases) of specimens. There was no local recurrence among the patients treatedwith any additional treatment. Limitations: Single-center, retrospective studydesign Conclusions: In ESD for EGC, multiple lateral margin involvement wasrelated to the histological characteristics such as extremely well differentiatedadenocarcinoma and histologic heterogeneity.

Sa1573Endoscopic Submucosal Dissection (ESD) -Prospective Study forthe Expanded Indication- for Undifferentiated Early GastricCancer (Ud-EGC)Risato Takeda*, Tomoki Michida, Kazuhiro Murai, Yuto Shiode,Hisashi Jo, Yugo Kai, Yuki Matsumura, Rie Morita, Hisaaki Kita,Tamiko Saito, Tomoyo Kanno, Yuki Nakada, Miho Chiba,Kosaku Maeda, Masafumi Naito, Toshifumi ItoInternal Medicine, Osaka Koseinenkin Hospital, Osaka, JapanIntroduction: ESD has become a promising endoscopic treatment for EGCwithout lymph node metastasis. Recently, undifferentiated type intramucosalcancers without ulcer findings less than 20mm in size could be chosen asendoscopic treatment lesions for expanded indication because of a negligiblerisk of lymph node metastasis (Gastric Cancer. 12: 148-52, 2009). However, it isnot well reported the efficacy of ESD for the UD-EGC. Aim: The aim of thisstudy was to elucidate efficacy of ESD for the UD-EGC. Methods: We designed aprospective study in which ESD was applied in patients with UD-EGC. Accordingto final diagnosis after the ESD, UD-EGC less than 20mm in size withoutulceration, considered to have hardly metastasis, were enrolled and followed upand otherwise were advised to be operated on additionally. The protocol wasapproved by ethics committee of our hospital, and consent to take part in thestudy was obtained from patients. Curative resection was defined if the lateraland vertical margins of the UD-EGC above were free of tumor pathologically.Followed-up endoscopic examinations are performed 6 months later, and theevery 6 months. Results: From April 2006 to September 2012, ESD wasperformed in 23 patients (13 men and 10 women with a median age of 69years). Mean follow-up periods were 31 months (range, 1-67). The mean tumorsize was 17mm (range, 4-48). As for the depth, 20 (87%) were mucosal cancers,and 3 (13%) were submucosal ones. Lymphovascular involvement was positivein 2 patients. Three had a positive lateral margin. Consequently, 15 (65%) werediagnosed as non-curative resections mainly because of more than 20mm in size,or cancers with ulceration. Among them, 12 patients received additionaloperations. Nodal metastasis was recognized in 1 patient, and 2 patients withpositive lateral margin had residual of cancer. In the remaining patients, no caseof local recurrence or distant metastasis was observed during the follow-up.Conclusions: ESD could provide accurate histological diagnosis by resecting UD-EGC en-bloc. Curative resection was hard to be obtained because of difficultiesin preoperative diagnosis. In case of curative resection, ESD would be feasiblefor treatment for UD-EGC.

Sa1574“Scissorhands” Technique for Gastric ESD Using Novel Gel andEndoscopic ScissorsMouen Khashab*, Payal Saxena, Reem Z. Sharaiha,Ali Kord Valeshabad, Yamile Haito Chavez, Venkata S. Akshintala,Gerard L. Aguila, Faming Zhang, Anthony N. Kalloo, Pankaj J. PasrichaJohns Hopkins Medical Institute, Baltimore, MDBackground: Endoscopic submucosal dissection (ESD) has developed into anaccepted therapy for early gastrointestinal neoplasia, especially in Asiancountries. A major advantage of ESD is that it allows en bloc resection and,therefore, decreases the risk of neoplastic recurrence. Western endoscopists havenot embraced ESD nearly as readily as their Eastern counterparts due to amultitude of factors, including procedural complexity and risks. We havepreviously shown that a novel viscous gel (Cook Medical) has submucosaldissecting properties and can facilitate ESD. Aims: To study feasibility andprocedural times of gastric ESD using a novel gel and endoscopic scissors(FlexShears, Apollo Endosurgery). Methods: Simulated 3cm gastric submucosallesions were created by initial submucosal injection of 10-15ml of saline with0.3% indigo carmine followed by placement of a 10mm embolization coil intothe bleb using 19-gauge EUS needle. Subsequently, the gel was injected into the

submucosal bleb using a 19-gauge needle and a custom-made injector apparatus.Needle knife was used to create an initial incision when needed. Endoscopicscissors was then used for circumferential incision around created lesions. Theinserted coil (i.e. submucosal lesion) was then removed. The submucosal surfacewas carefully examined for signs of injury. Procedural times were recorded.Results: ESD was performed in four consecutive pigs using the “Scissorhands”technique. A total of 10cc of the gel was injected into the submucosal space ineach pig. Small submucosal incision was created using needle knife in the firstpig and electrocautery was not used in the remaining 3 experiments.Circumferential incision using the scissors was performed successfully in all pigs.The gel extruded through incision sites, was easily suctioned through theworking channel of the endoscope, and did not interfere with endoscopicvisualization. Submucosal dissection was not required in any case. “Auto-dissection” of created lesions by the gel was noted to be complete in all cases.Inserted coils were noted in the submucosal space during all experiments andwere removed by suctioning through the scope or by using biopsy forceps. Alllesions were successfully resected en bloc. There were no signs of deepsubmucosal or muscularis propria injury. In addition, bleeding did not occur inany of the four experiments. The average procedure time was 19 minutes (range13-22 minutes). Conclusion: Our novel technique of using endoscopic scissorsfor circumferential incision and gel for submucosal dissection permitted easy,safe and efficient gastric ESD. Electrocautery may be avoided as may adverseevents (e.g. perforation). The “Scissorhands” ESD technique has the potential torevolutionize ESD if its safety and efficacy are replicated in other animal studiesand subsequently in human trials.

Sa1575Pathological Assessment of Early Gastric Cancer Treated byEndoscopic Submucosal Dissection; Including HistologicallyMixed TypeKen Ohnita*1, Hajime Isomoto1, Hitomi Minami1, Kayoko Matsushima1,Yuko Akazawa1, Naoyuki Yamaguchi1, Fuminao Takeshima1,Tomayoshi Hayashi2, Saburo Shikuwa3, Kazuhiko Nakao1

1Gastroenterology and Hepatology, Nagasaki University Hospital,Nagasaki, Japan; 2Department of Pathology, Nagasaki UniversityHospital, Nagasaki, Japan; 3Department of Internal Medicine,Sankoukai Miyazaki Hospital, Isahaya, JapanBackground and Aim: Endoscopic submucosal dissection (ESD) for early gastriccancer has been performed for selected undifferentiated carcinomas as indicationof ESD has expanded. Differentiated adenocarcinomas also occasionally containundifferentiated components. The aim of this study was to clarify invasion ofdepth and lymphovascular invasion in different histological types, especially indifferentiated/undifferentiated mixed-type early gastric cancers. Patients andMethods: A total of 1505 early gastric cancers were treated with ESD from January2001 to December 2011. The cases were histologically classified into four groups(group A: only differentiated component, group B: differentiated component �undifferentiated component, group C: undifferentiated component � differentiatedcomponent, group D: only undifferentiated component). Group A was furtherclassified into four subgroups (group A1: well differentiated adenocarcinoma (tub1),group A2: moderately differentiated adenocarcinoma (tub2), group A3: papillaryadenocarcinoma (pap), group A4; mixed type of tub1, tub2, and/or pap). Weinvestigated the following three items; (1) Depth and lymphovascular invasionamong group A, B, C and D (2) Depth and lymphovascular invasion among groupA1, A2, A3 and A4 (3) Frequency of containing undifferentiated carcinomacomponent in each main histological type (tub1, tub2, and pap) in group A and B.Results: (1) Rate of SM2 invasion in group A was significantly lower than in othergroups (5.5%, 39.8%, 38.9%, and 28.0% in group A, B, C and D, respectively,p�0.0001). In parallel, rate of lymphovascular invasion in group A was alsosignificantly lower in than other groups (5.5%, 35.0%, 27.8%, and 28.0% in ingroup A, B, C and D, p�0.0001). (2) Among group A, SM invasion rate in groupA1 were significantly lower than group A2 and A4 (2.4%, 16.9%, and 11%, ingroup A1, A2, and A4, respectively, p�0.0001). Frequency of lymphovascularinvasion in A1 were significantly lower than in group A2 and A4 (2.5%, 22.5%,and 10.9%, in group A1, A2, and A4, respectively p�0.0001). (3) Frequency ofcontaining undifferentiated carcinoma component in tub1 group was significantlylower than in tub2 group and pap group (2.1%, 27.8%, and 8.8%, tub1, tub2, andpap, respectively, tub1 vs tub2: p�0.0001, tub1 vs pap: p�0.05). Conclusions;Rate of SM2 invasion and lymphovascular invasion were higher in the casescontaining undifferentiated components than in those without undifferentiatedcomponents. Although tub2 is classified as differentiated type, incidence of SM2invasion, lymphovascular invasion, and mixture of undifferentiated componentswere relatively high thus may warrant extra attention.

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www.giejournal.org Volume 77, No. 5S : 2013 GASTROINTESTINAL ENDOSCOPY AB255