title: High incidence of metachronous advanced adenoma and cancer after endoscopic resection of colon polyps ≥20 mm in size.
abstract: OBJECTIVE
  There are limited studies on incidence rates of metachronous neoplastic lesions after resecting large colorectal polyps. In the present study, we analyzed metachronous lesions after endoscopic resection of colorectal polyps ≥20 mm in size.
  
  
  METHODS
  We retrospectively analyzed consecutive patients who underwent endoscopic resection of polyps from 2006 to 2013 at two affiliated hospitals. All patients underwent at least two total colonoscopies before follow up to ensure minimal missed polyps. Only patients who had follow-up colonoscopy annually after resection were recruited. We separated patients according to size of polyp resected; there were 239 patients in the ≥20-mm group and 330 patients in the <20-mm group. Clinical characteristics and cumulative rates of metachronous advanced adenoma and cancer in both groups were analyzed. Advanced adenoma was defined as a neoplastic lesion ≥10 mm in size and adenoma with a villous component.
  
  
  RESULTS
  Cumulative rate of development of metachronous advanced adenoma and cancer in the ≥20-mm group was significantly higher than in the <20-mm group (22.9% vs. 9.5%, P < 0.001) at 36 months. There was also more development of small polyps 5-9 mm in the ≥20-mm group than in the <20-mm group (45.2% vs. 28.8%, P < 0.001). With respect to metachronous lesions, there were more right-sided colonic lesions in the ≥20-mm group than in the <20-mm group (78.8% vs. 50.0%, P = 0.015).
  
  
  CONCLUSIONS
  High incidence rates of development of metachronous neoplastic lesions were detected after resection of colorectal polyps ≥20 mm in size.
authors.affiliation: Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Singapore.
authors.forename: Naohisa
authors.initials: N
authors.lastname: Yoshida
authors.affiliation: Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Singapore.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Naito
authors.affiliation: Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Singapore.|Division of Gastroenterology & Hepatology, University Medicine Cluster, National University Hospital, Singapore.
authors.forename: Kewin Tien Ho
authors.initials: KT
authors.lastname: Siah
authors.affiliation: Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Singapore.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Murakami
authors.affiliation: Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Singapore.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ogiso
authors.affiliation: Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Singapore.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Hirose
authors.affiliation: Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Singapore.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Inada
authors.affiliation: Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Singapore.
authors.forename: Ken
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Singapore.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Konishi
authors.affiliation: Department of Gastroenterology, Maizuru Medical Center, Kyoto, Japan.
authors.forename: Munehiro
authors.initials: M
authors.lastname: Kugai
authors.affiliation: Department of Gastroenterology, Matsushita Memorial Hospital, Osaka, Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Morimoto
authors.affiliation: Department of Gastroenterology, Ayabe City Hospital, Osaka, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hasegawa
authors.affiliation: Department of Gastroenterology, Nara City Hospital, Nara, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kanemasa
authors.affiliation: Department of Gastroenterology, Otsu City Hospital, Shiga, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Wakabayashi
authors.affiliation: Department of Gastroenterology, Murakami Memorial Hospital, Gifu, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Yagi
authors.affiliation: Department of Surgical Pathology, Graduate School of Medical Science, Kyoto, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Yanagisawa
authors.affiliation: Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Singapore.
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Itoh
mesh_terms: D000236:Adenoma / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D000368:Aged; D003110:Colonic Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D003111:Colonic Polyps / Q000175:diagnosis / Q000601:surgery*; D003113:Colonoscopy / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D009367:Neoplasm Staging; D016609:Neoplasms, Second Primary / Q000175:diagnosis / Q000453:epidemiology*; D011183:Postoperative Complications / Q000453:epidemiology*; D012189:Retrospective Studies; D013997:Time Factors
keywords: colorectal cancer; colorectal polyp; endoscopic mucosal resection (EMR); endoscopic submucosal dissection (ESD); metachronous lesion