title: Stretching Causes Extensive Changes of Gastric Submucosa: Is It Acceptable to Define 500 microm as the Safe Margin?
abstract: OBJECTIVE
  Endoscopic mucosal resection can cure early gastric cancer. The risk of lymphatic metastasis is related to the depth of submucosal invasion by the mucosal malignancy, with a resection depth of 500 microm generally accepted as a safe cut-off. However, excessive thinning induced by stretching of the resected tissue sometimes preventing a precise diagnosis. We studied the effects of stretching on different layers and sites of gastric tissue.
  
  
  METHODS
  Porcine stomachs were cut into 2.0x2.0 cm pieces, and pieces from body were stretched to 2.5, 3.0, and 3.5 cm. Pieces from the cardia, body, and antrum were also stretched to 3.0 cm. The thickness of each layer was measured and analyzed statistically.
  
  
  RESULTS
  Whole gastric wall and submucosal layers showed gradual thinning, with stretching to 3.5 cm tearing the tissues and resulting in imperfect extension. The submucosa was thinner in body tissue than in cardia and antrum tissues. Stretching to 3.0 cm induced a consistent decrease in submucosal thickness (30-70%). The change in thickness varied widely between individual samples.
  
  
  CONCLUSIONS
  A resection margin of 500 microm might be insufficient for the complete removal of malignancy. Moreover, the thickness of the submucosal layer differs with the gastric site and between individuals. Future studies are needed to confirm the findings in human tissue.
authors.affiliation: Institute of Digestive Disease and Nutrition, Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea.
authors.forename: Sanghoon
authors.initials: S
authors.lastname: Park
authors.forename: Hoon Jai
authors.initials: HJ
authors.lastname: Chun
authors.forename: Yong Dae
authors.initials: YD
authors.lastname: Kwon
authors.forename: Bora
authors.initials: B
authors.lastname: Keum
authors.forename: Yeon Seok
authors.initials: YS
authors.lastname: Seo
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Kim
authors.forename: Yoon-Tae
authors.initials: YT
authors.lastname: Jeen
authors.forename: Soon Ho
authors.initials: SH
authors.lastname: Um
authors.forename: Chang Duck
authors.initials: CD
authors.lastname: Kim
authors.forename: Ho Sang
authors.initials: HS
authors.lastname: Ryu
authors.forename: Ji Hye
authors.initials: JH
authors.lastname: Lee
authors.forename: Yang-Seok
authors.initials: YS
authors.lastname: Chae