Mo1554 Grading Atrophic Gastritis by a New Quantitative Method Using Confocal LASER Endomicroscopy Probe (P-CLE): First Results of a Prospective Cohort Study

Mo1553 Is the Recent Who Pathological Classification for Gastric Cancer Helpful in Applying to Endoscopic Resection? Hae Won Kim*, Jie-Hyun Kim, Hyunki Kim, Hoguen Kim, Yong Chan Lee, Sang Kil Lee, Sung Kwan Shin, Yong Hoon Kim, Jun Chul Park, DA Hyun Jung, Jae Jun Park, Young Hoon Youn, Hyojin Park, Sung Hoon Noh, Seung Ho Choi Gastroenterology, Seoul, Korea (the Republic of); pathology, Yonsei university college of medicine, Seoul, Korea (the Republic of); Surgery, Yonsei college of medicine, Seoul, Korea (the Republic of) Background/Aims: Endoscopic resection (ER) has been performed in early gastric cancer with undifferentiated histology (UD-EGC) based on Japanese classification. Whereas, we previously found that different approach is necessary between poorly differentiated (PD) & signet ring cell carcinoma (SRC) for curative resection. However, according to 2010 WHO classification, diffuse type PD and SRC are categorized into the same group as poorly cohesive carcinoma. Thus, we assessed whether the WHO classification is helpful to perform ER of UD-EGC. Methods: Among 3,419 EGC underwent surgery, we analyzed the clinicopathologic features of 1,295 lesions with SRC and PD. We recategorized into intestinal PD, poorly cohesive carcinoma (SRC, diffuse PD), and compared in terms of clinical behavior such as lymph node metastasis (LNM). We also recategorized 190 lesions (63 PD; 127 SRC) treated by ER into intestinal PD, poorly cohesive carcinoma (SRC, diffuse PD), and compared in terms of outcomes of ER. Results: According to surgical data, the rate of LNM was high in order from intestinal PD, diffuse PD and SRC (15.8%, 13.5%, and 6.3%). Similarly, the rate of LVI was significantly lowest in SRC compared with diffuse and intestinal PD. When compared between diffuse PD and SRC categorized as poorly cohesive carcinoma, the rate of LNM and LVI was significantly higher in diffuse PD than SRC. According to ER data, there was no recurrence in all of them if curatively resected. However, the most common cause of non-curative resection was different between SRC and PD irrespective of intestinal or diffuse type. The most common cause was positive lateral margin in SRC, whereas positive vertical margin in both intestinal and diffuse PD. Conclusions: Clinical behaviors are different between diffuse PD and SRC categorized as poorly cohesive carcinoma in WHO classification. Considering LNM and outcomes of ER, the recent WHO classification may not be helpful to perform ER for UD-EGC.