Tu1420 The Comparison of K-RAS Mutation in Colorectal Muscularis Propria Carcinoma According to Morphological Developments

Abstract

ADR. Both indexes, ADR and PDR, may not be sufficient. We developed the Multiple PDR (mPDR), the Zonal PDR (zPDR) and Multiple Zonal PDR (mzPDR) (Figure 1). We conducted a retrospective multiple center study enrolling 1640 patients who were scheduled for elective colonoscopy between January 2010 and October 2012. Polyp size, location and macroscopic classification as Paris scale were determined by five skilled endoscopists. We divided all patients in two arms, age and sex matched. Indications and percentages in/outpatients were also comparable between two arms. The first arm (Control Group) was constituted by 1121 endoscopic examinations made without assessment of the bowel cleansing, only recording the parameters linked to the PDR. This group was used to evaluate the impact of the proposed parameters of a numerically significant sample. The second arm (Study Group) was constituted by 519 patients. In this second arm, endoscopists performed an evaluation on global bowel cleaning score by the Aronchick scale (A). In addition, other new parameters proposed were considered. Considering the BP, a statistical significance between the A 1-2 group and the A 4-5 group PDR, mPDR and mzPDR was determined (Figure 2). Analyzing the mzPDR, a significant decrease of the diagnostic accuracy, compared to other proposed parameters, it has been demonstrated. Our preliminary results suggest a great impact of BP on polyp detection, also considering the ability of diagnosing colon polyps in different colonic segments. Thus, BP classifications indicating a total value, without a single segment description, could be not always sufficient. The PDR remains the parameter currently most effective to determine the diagnostic accuracy during colonoscopy. However, the zPDR and mzPDR could effectively complete the PDR in order to analyze different colic segments. Our study also highlights a difficulty in the proper BP evaluation when this is not clearly “excellent” or “poor”. Tu1420 The Comparison of K-RAS Mutation in Colorectal Muscularis Propria Carcinoma According to Morphological Developments Tomokazu Hisayuki*, Shin-Ei Kudo, Shigeharu Hamatani, Hideyuki Miyachi, Katsuro Ichimasa, Hiromasa Oikawa, Yuichi Mori, Masashi Misawa, Toyoki Kudo, Kenta Kodama, Yoshiki Wada, Takemasa Hayashi, Kunihiko Wakamura, Eiji Hidaka, Fuyuhiko Yamamura, Shogo Ohkoshi, Fumio Ishida, Jun-Ichi Tanaka Digestive Disease Center, Showa University Northern Yokohama Hospital, Yokohama, Japan; Department of Pathology, Showa University Northern Yokohama Hospital, Yokohama, Japan Aim: To investigate differential expression of K-ras mutation in depressed-type lesion in comparison with polypoidor flat types. Methods: A total of 19800 neoplasms were resected endoscopically or surgically at our unit from April 2001 to December 2011. Of these 347 muscularis propria carcinoma were included. Thirty specimens of MP carcinoma were obtained by surgical resection or endoscopic submucosal dissection. According to their morphological developments, we classified them into three types: polypoid(n 10), flat(n 10), and depressed types(n 10). K-ras mutation was examined using reverse sequence-specific oligonucleotide with polymerase chain reaction method(PCR-rSSO).. Results: Singlebase transition from GGT to GAT in codon 12 was detected in five samples, and four samples presented with GGC to GAC transition in codon 13. Our study showed a high frequency of G to A transition of codon 12 mutation of the K-ras gene. K-ras mutation was found in polypoid type by 40%(4/10), flat type by 70%(7/10), and depressed type by 20%(2/10). To explain flat type in detail, eight LST-G and two LSTs-NG (pseudo-depressed type) were included in flat-type lesions. Seven(87.5%) of 8 LST-G had K-ras mutation, while two LSTs-NG had no K-ras mutation(0/2). In summary, the frequency of K-ras mutation was significantly lower in depressed-type lesions and LSTs-NG (pseudo-depressed type) [2/12(16.7%)] as compared to the other types [11/18(61.1%)] of MP carcinomas. Conclusions: Depressed-type lesions and LST-NG (pseudo-depressed type) were suggested to come through a distinct genetic pathway.