T1422

Validation of an Algorithm for Classifying Interval Colorectal

Cancer Occurrence: Prostate, Lung, Colorectal, and Ovarian

(PLCO) Cancer Screening TrialAjay Pabby, Joel L. Weissfeld, Paul F. Pinsky, Richard B. Hayes, RobertE. SchoenObjective: We previously published an algorithm for classifying colorectal cancers(CRC) detected after colonoscopy (Gastrointest Endosc 2005;61:385-391). Tovalidate our algorithm, it is important to apply this to cancers detected underdifferent circumstances or in other trials. Methods: The Prostate, Lung, Colorectal,and Ovarian (PLCO) cancer screening trial is a large, community-based, randomizedcontrolled trial evaluating screening flexible sigmoidoscopy (FS). Subjects witha positive screening FS who were referred for follow up, but had distal cancerdetected subsequent to their initial colonoscopy comprise the study group. Canceroccurrences were classified into one of five potential categories: 1) incompleteremoval (cancer at the site of previous adenoma based on depth of insertion andanatomic segment); 2) failed biopsy detection (cancer in an area of suspectedneoplasia with negative biopsy specimens); 3) incomplete examination (canceroccurring beyond the depth of insertion of prior colonoscopy); 4) missed cancer(large, advanced stage cancer found at a short interval after colonoscopy); and 5)new cancer (small or early stage cancer after a longer interval). Results: Elevensubjects had a distal CRC diagnosed subsequent to their colonoscopy. The meantime interval from initial colonoscopy to CRC diagnosis was 42.8 months (range11-84 months). Using our algorithm, the 11 cancers were classified as incompleteremoval (7), failed biopsy detection (0), incomplete examination (1), missed cancer(2), and new cancer (1). 6/7 incomplete removal cases occurred in the rectum with4/7 initially diagnosed with an advanced adenoma at the same site. Missed cancersoccurred where a large polyp (1 cm and 3 cm) had been seen on prior FS, but notduring colonoscopy. Conclusion: Our algorithm for interval cancers occurring aftercolonoscopy is applicable to CRC occurring subsequent to colonoscopy aftera positive screening FS. Quality improvements should include careful attention todetect all abnormalities seen on previous examinations and assurance of completeremoval of large or advanced adenomas, especially in the rectum.

T1423

A Study of Normal Intestine Using Confocal EndomicroscopyIsao Odagi, Tomohiro Kato, Hisao TajiriBackground: Advances in endoscopy provide new options for diagnosis, howeverbiopsy is still required in many cases to obtain definitive histopathology. Confocalendomicroscopy (CEM) (OptiScan Ltd., Australia and Pentax Ltd., Tokyo, Japan) isa newly developed system that uses a laser confocal system together witha conventional endoscope to provide additional digital information about the tissuesurface, subsurface morphology and microstructure. Fluorescent imaging permitsmagnification up to 1000 times, resolution of 1 mm and a focal imaging depth of250 mm. In this study, we evaluated CEM as a tool for conducting virtual biopsies ofthe colon by comparing structure and architecture in CEM images with biopsyhistopathology of normal colon. Methods: All patients undergoing CEM gaveinformed consent according to a protocol approved by the Research EthicsCommittee of The Jikei University School of Medicine. The large intestines of 43patients (31 males and 12 females), with an average age of 63 years (range, 38 to 75years) were examined using an intravenous injection of fluorescein with CEM tofacilitate correlation of images taken in vivo with biopsied samples. CEM imageswere compared with conventional histopathology of biopsies. For correlation withCEM images, injected fluorescein was localized immunohistochemically with theavidin-biotin complex (ABC) immunoperoxidase technique using mousemonoclonal antibody to fluorescein as the primary antibody. Results: CEM imageswere observed continuously from the surface to the mid crypt level in normal areasof large intestine. All CEM images were concordant histopathologically with biopsyobservations. CEM images documented blood flow in the capillaries surroundingcrypts and mucus release from crypts, observations which may prove useful forevaluating physiological function. Positive staining was seen in the interstitium,capillary walls and at the mucosal surface of crypts. The cytoplasm of mucosalsurface enterocytes was stained but not their nuclei nor the mucus of goblet cells.CEM image localization of fluorescein was consistent with immunohistochemicallocalization. Conclusions: CEM provides endoscopists with a potentially valuablenew diagnostic tool, not only for observing tissue in situ at the histopathologicallevel, but also for the coincident evaluation of physiological functions includingblood flow and mucus production during endoscopy.

T1424

Safe and Painless Insertion in ColonoscopyToshinori Kurahashi, Kazuhiro Kaneko, Hiroaki Ito, Taikan Yamamoto,Yosuke Kumekawa, Meiko Kuwahara, Yutaro Kubota, Takashi Muramoto,Michio ImawariBackground and Aims: Colonoscopy is a superior tool for detection, diagnosis andtreatment of colorectal neoplasia. However, it is frequently difficult to insert thecolonoscopy because of a long colon, diverticular disease, or history of abdominalsurgery. When the colonoscope is not inserted straightly in passing throughrectosigmoid (RS) or sigmoid-descending colon (S-D) junction, patients often haveabdominal pain. The aim of this prospective study is to assess the relationshipsbetween the passage patterns and presence of pain, insertion time from anal vergeto cecum, the history of abdominal surgery, presence of diverticular disease, age,body mass index (BMI), or gender. Materials and Methods: Two colonoscopists withextensive experience performed total colonoscopy in 329 patients withoutcomplaint of abdominal pain at Showa University Hospital from April 2005 throughNovember 2005. The passage patterns in colonoscopic insertion were definedaccording to whether loops are formed in passing through the RS or S-D junction.We classified passing pattern into push insertion pattern which made loops such asN-loop, alpha-loop or double loop to pass through RS or S-D junction and straightinsertion pattern which passed up the S-D junction within scope length ofapproximately 30 cm as a result of making no loops. Results: The straight insertionpattern and push insertion pattern were found in 214 patients (65%) and 115patients (35%), respectively. The frequency of painlessness was significantly higherin straight insertion group (205 of 214: 96%) than in push insertion group (47 of115: 41%, p ! 0.0001). The mean insertion time from anal verge to cecum wassignificantly shorter in straight insertion group (4.9 G 2.4 minutes) than in pushinsertion group (11.2 G 5.2 minutes, p ! 0.0001). The frequency of history ofabdominal surgery was significantly higher in push insertion group (45 of 115: 39%)than in straight insertion group (60 of 214: 28%, p Z 0.04). The frequency of femalegender was significantly higher in push insertion group (54 of 115; 47%) than instraight insertion group (68 of 214: 32%, p Z 0.006). No significant differenceswere seen in age, BMI and the presence of diverticular disease between push andstraight insertion groups. We observed no serious complication during orimmediately after colonoscopy in all patients. Conclusions: It is important for safeand painless colonoscopy to prevent loop formation and to keep the scope axisstraight in the RS and S-D junction. Colonoscopists should pay attention to femalepatients or patients with history of abdominal surgery.

T1425

Risk Factors of Lymph Node Metastasis of Colorectal Cancer;

Analysis of 2502 Consecutive Cases Detected with ColonoscopySatoshi Takano, Jun Kato, Yasushi ShiratoriBackground and Aim: Colorectal cancer (CRC) patients with lymph node metastasishave poorer prognosis than those without lymph node metastasis. Since accuratediagnosis of lymph node metastasis requires careful surgical resection andhistological examination, it is useful to know the risk for presence of lymph nodemetastasis at cancer resection. The aim of this study is to identify predicting factorsof the presence of lymph node metastasis in CRC patients. Subjects and Methods:Total 2502 consecutive CRC patients who underwent colonoscopy and surgicaloperation at our institutes with accurate information of presence or absence oflymph node metastasis were analyzed. Univariate and multivariate analysis wereperformed to identify risk factors for presence of lymph node metastasis usingparameters of patient factors (age, gender, reasons for receiving colonoscopy, andpresence or absence of synchronous adenomas), and tumor factors (tumorlocation, size, histology, and depth of invasion). Results: Of all analyzed subjects,1192 (48%) patients had lymph node metastasis. Univariate analysis indicated thatage less than 50 years (8% vs. 6%, p ! 0.05), undergoing colonoscopy due toabdominal pain or altered bowel habit (24% vs. 13%, p ! 0.001, and 12% vs. 8%,p ! 0.01, respectively), tumor located in right colon (36% vs. 30%, p ! 0.01),depth of invasion at T3 or T4 (90% vs. 58%, p ! 0.001), tumor size R20 mm (94%vs. 81%, p ! 0.001), uncommon or undifferentiated histology (11% vs. 4%,p ! 0.001) were more frequently observed in CRC (or CRC patients) with lymphnode metastasis than those without lymph node metastasis. On the other hand,undergoing colonoscopy due to positive fecal occult blood test (37% vs. 21%,p ! 0.001), and presence of synchronous adenomas (48% vs. 36%, p ! 0.001) weremore frequently seen in CRC patients without lymph node metastasis. Multivariateanalysis revealed that abdominal pain as the indication of colonoscopy (OR;1.276,95%CI 1.008-1.965), depth of invasion at T3 or T4 (OR;5.617, 95%CI 4.019-6.636),uncommon or undifferentiated histology (OR;1.970, 95%CI 1.394-2.784), wereidentified as the independent predicting factors of lymph node metastasis.Meanwhile, undergoing colonoscopy due to positive fecal occult blood test(OR;1.265, 95%CI 1.019-1.570), and presence of synchronous adenomas (OR;1.344,95%CI 1.128-1.601) were the independent factors associated with being free fromlymph node metastasis.

Abstracts

AB220 GASTROINTESTINAL ENDOSCOPY Volume 63, No. 5 : 2006 www.giejournal.org