title: Spatially selective laser coagulation of the gastric wall: a new methodology.
abstract: BACKGROUND
  The incidence of lymph node metastasis is low in early gastric cancer. Early cancer without nodal metastasis may be theoretically eradicated by local treatment alone. However, except for gastrectomy, there exists no reliable treatment for submucosal cancer. We present a new laser system which irradiates the gastric wall from the serosal side combined with synchronous serosal cooling that can produce deep thermal coagulation without transmural damage.
  
  
  METHODS
  A laser handpiece with a built-in surface cooling system has been devised, employing a diode laser of 980 nm wavelength. Animal experiments were conducted to ascertain whether this laser system could coagulate the mucosa and submucosa with acceptable injury to the muscular layer and serosa. The gastric wall was irradiated from the serosal side with synchronous serosal cooling at 6.0-10.0 W power output and 50-400 s exposure time. The degree and depth of damage were histologically assessed after 7 days.
  
  
  RESULTS
  Ninety-one points were irradiated in 8 dogs. Mucosal coagulation was observed during the treatment while the serosa showed no serious injury. No gastric perforation occurred up to 7 days later. Histologically, the damage did not penetrate the gastric wall except for cases where 10.0 W and 400 s were used. Cauterization of the mucosa and submucosa with acceptable muscle layer damage was achieved in selected settings.
  
  
  CONCLUSIONS
  This laser system enables thermal coagulation of the gastric mucosa and submucosa with acceptable muscle layer damage. This makes it a promising, novel, minimally invasive treatment for submucosal cancer.
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. MAEMA-2SU@h.u-tokyo.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Maema
authors.forename: Daijo
authors.initials: D
authors.lastname: Hashimoto
authors.forename: Sadao
authors.initials: S
authors.lastname: Yokoya
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shoji
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Makuuchi
mesh_terms: D000818:Animals; D004285:Dogs; D005753:Gastric Mucosa / Q000473:pathology / Q000601:surgery*; D017075:Laser Coagulation / Q000295:instrumentation / Q000379:methods*; D019060:Minimally Invasive Surgical Procedures; D013274:Stomach Neoplasms / Q000556:secondary / Q000601:surgery*