title: Right-side shift of metachronous colorectal adenomas after polypectomy.
abstract: OBJECTIVE
  In our previous study, we showed that the development of adenomas in the right-side colon increased with aging in subjects with no colorectal neoplasms. The aim of the present study was to investigate the location of metachronous colorectal adenomas after endoscopic polypectomy.
  
  
  METHODS
  The records of a colonoscopic follow-up study on 2900 subjects after polypectomy were analyzed. The location was classified as the right-side colon and left-side colon at the splenic flexure. Subjects were classified into three groups according to distribution of adenomas at the initial two colonoscopies: those with adenomas located only in the left side (LL), adenomas in both the left side and right side (LR), and adenomas only in the right side (RR). Distribution of initial and metachronous adenomas was evaluated according to age.
  
  
  RESULTS
  The annual incidence rates of colorectal adenomas in the left-side colon were estimated to be 8.56%, 11.2%, and 5.71% in the LL, LR, and RR groups, respectively. The rates in the right side were 5.91%, 15.5%, and 9.38%, respectively. The incidence rates in the left side in the age groups <40, 40-49, 50-59, and > or =60 years were 6.93%, 8.08%, 8.33%, and 8.48%/year, respectively. Those in the right side were 4.91%, 7.27%, 9.86%, and 12.41%/year, respectively.
  
  
  CONCLUSIONS
  Although there may be individual predilection for right-side or left-side location of colorectal adenomas, aging tends to increase the number of adenomas in the right-side colon, while only modestly affecting those in the left-side colon.
authors.affiliation: Department of Gastroenterology, University of Tokyo, Bunkyo-ku, Tokyo, Japan. yamaji-tky@umin.ac.jp
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yamaji
authors.forename: Toru
authors.initials: T
authors.lastname: Mitsushima
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Yoshida
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Watabe
authors.forename: Makoto
authors.initials: M
authors.lastname: Okamoto
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ikuma
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Wada
authors.forename: Takao
authors.initials: T
authors.lastname: Kawabe
authors.forename: Masao
authors.initials: M
authors.lastname: Omata
mesh_terms: D000236:Adenoma / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery*; D000328:Adult; D000367:Age Factors; D016009:Chi-Square Distribution; D003111:Colonic Polyps / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery*; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery*