title: Estimation of subepithelial lateral extent in submucosal early gastric cancer: retrospective histological analysis.
abstract: BACKGROUND
  Endoscopic full-thickness resection (EFTR) is expected to make possible minimally invasive local resection of early gastric cancer (EGC). However, no consensus exists regarding how far an optimal safety margin should be set in determining the resection area by endoscopy. We aimed to investigate the optimal lateral margin of EGC which could be a candidate for EFTR by measuring the subepithelial extent (SE) of tumors.
  
  
  METHODS
  In 60 surgically resected submucosal EGCs 4 cm or smaller, 595 prepared slides which showed lateral tumor borders both on the epithelial surface and on the subepithelial layer were assessed. The distance between the epithelial and the subepithelial tumor edge was measured under microscopic observation, followed by analyses of the relationship between the measured SE and the histological characteristics.
  
  
  RESULTS
  The average and the median SE were 1.1 mm (standard deviation 1.8 mm) and 0.3 mm (range 0-12.3 mm), respectively. The 99th percentile was 8.8 mm. With regard to the histological type, the median SE was significantly greater in diffuse-type tumor than in intestinal-type tumor (0.9 mm vs 0 mm, p < 0.0001). With regard to the location of the subepithelilal tumor edge, the median SE was significantly greater in the submucosal layer than in the mucosal layer (2.6 mm vs 0.3 mm, p < 0.0001).
  
  
  CONCLUSIONS
  In most lesions, the SE was less than 1 cm. A safety margin may be set at 1 cm in EFTR of submucosal EGC.
authors.affiliation: Division of Research and Development for Minimally Invasive Treatment, Cancer Center, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Goto
authors.affiliation: Division of Research and Development for Minimally Invasive Treatment, Cancer Center, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Ai
authors.initials: A
authors.lastname: Fujimoto
authors.affiliation: Department of Pathology, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Shimoda
authors.affiliation: Division of Research and Development for Minimally Invasive Treatment, Cancer Center, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Yasutoshi
authors.initials: Y
authors.lastname: Ochiai
authors.affiliation: Department of Surgery, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Matsuda
authors.affiliation: Department of Surgery, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Hiroya
authors.initials: H
authors.lastname: Takeuchi
authors.affiliation: Department of Surgery, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kawakubo
authors.affiliation: Division of Research and Development for Minimally Invasive Treatment, Cancer Center, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Tadateru
authors.initials: T
authors.lastname: Maehata
authors.affiliation: Division of Research and Development for Minimally Invasive Treatment, Cancer Center, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Uraoka
authors.affiliation: Division of Diagnostic Pathology, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Kameyama
authors.affiliation: Department of Surgery, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kitagawa
authors.affiliation: Division of Research and Development for Minimally Invasive Treatment, Cancer Center, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan. yahagi.keio@gmail.com.
authors.forename: Naohisa
authors.initials: N
authors.lastname: Yahagi
mesh_terms: D000368:Aged; D005260:Female; D005753:Gastric Mucosa / Q000473:pathology; D005773:Gastroscopy / Q000592:standards*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010340:Pathology, Surgical / Q000592:standards*; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000473:pathology* / Q000601:surgery*
keywords: Early gastric cancer; Endoscopic full-thickness resection; Subepithelial extent