title: Incidence of lymph node metastasis in intramucosal gastric cancer measuring 30 mm or less, with ulceration; mixed, predominantly differentiated-type histology; and no lymphovascular invasion: a multicenter retrospective study.
abstract: BACKGROUND
  Intramucosal gastric cancer, ≤3 cm (≤30 mm) with ulceration, and mixed histology (predominantly differentiated), was previously considered curative after endoscopic resection, and additional surgery was thought to be unnecessary. However, as the evidence base for these criteria remains insufficient, the Japanese Gastric Cancer Treatment Guidelines, ver. 3 (2010) specify that this pathology should be considered noncurative and recommend additional surgery. We report the frequency of lymph node metastasis in patients with these conditions based on a multicenter study.
  
  
  METHODS
  Of patients with early gastric cancer who underwent gastrectomy with lymph node dissection, those with a mixed, predominantly differentiated tumor type, ulceration, a tumor diameter ≤3 cm, and no lymphovascular invasion were entered into this study.
  
  
  RESULTS
  Four hundred and seven patients met the criteria, 21 of whom were excluded owing to a lack of available information. Thus, a total of 386 patients were included in the analysis, from 37 of the 42 member institutions. The mean study duration was 125 months. The most common combination of mixed histology was tub2 + por (67 %). None of the 386 patients had lymph node metastasis (95 % confidence interval, 0-0.8 %).
  
  
  CONCLUSIONS
  The results of this retrospective study indicate that the risk of lymph node metastasis was less than 1 % among patients with the criteria defined here, considered to be criteria for noncurative resection as per the current guidelines, and suggest that observation alone without additional surgery may result in a good outcome.
authors.affiliation: Division of Endoscopy, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumicho, Suntougun, Shizuoka, 411-8777, Japan. k.takizawa@scchr.jp.
authors.forename: Kohei
authors.initials: K
authors.lastname: Takizawa
authors.affiliation: Division of Endoscopy, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumicho, Suntougun, Shizuoka, 411-8777, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ono
authors.affiliation: Department of Gastroenterology, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, Tokyo, Japan.
authors.forename: Yorimasa
authors.initials: Y
authors.lastname: Yamamoto
authors.affiliation: Gastric Surgery Division, National Cancer Center Hospital, Tokyo, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Katai
authors.affiliation: Department of Endoscopy, National Hospital Organization Shikoku Cancer Center, Ehime, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Hori
authors.affiliation: Endoscopy Division, Department of Gastroenterology, National Cancer Center Hospital East, Kashiwa, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Yano
authors.affiliation: The Second Department of Internal Medicine, Osaka Medical College, Osaka, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Umegaki
authors.affiliation: Internal Medicine, Niigata Cancer Center Hospital, Niigata, Japan.
authors.forename: Shunya
authors.initials: S
authors.lastname: Sasaki
authors.affiliation: Department of Gastroenterology, Toranomon Hospital, Tokyo, Japan.
authors.forename: Toshiro
authors.initials: T
authors.lastname: Iizuka
authors.affiliation: Department of Gastroenterology, Yamagata Prefectural Central Hospital, Yamagata, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Kawagoe
authors.affiliation: Division of Pathology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Tadakazu
authors.initials: T
authors.lastname: Shimoda
authors.affiliation: Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Muto
authors.affiliation: Department of Upper Gastrointestinal Surgery, Hyogo College of Medicine, Hyogo, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Sasako
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology* / Q000556:secondary / Q000601:surgery; D002288:Adenocarcinoma, Mucinous / Q000453:epidemiology* / Q000556:secondary / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018279:Carcinoma, Signet Ring Cell / Q000453:epidemiology* / Q000556:secondary / Q000601:surgery; D002454:Cell Differentiation; D005260:Female; D005500:Follow-Up Studies; D005743:Gastrectomy; D005753:Gastric Mucosa / Q000473:pathology* / Q000601:surgery; D005773:Gastroscopy; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000473:pathology* / Q000601:surgery; D013276:Stomach Ulcer / Q000473:pathology* / Q000601:surgery; D055815:Young Adult
keywords: Additional indication; Early gastric cancer; Endoscopic submucosal dissection; Mixed histology; Undifferentiated adenocarcinoma