title: Repeat-screening colonoscopy 5 years after normal baseline-screening colonoscopy in average-risk Chinese: a prospective study.
abstract: OBJECTIVE
  Although colonoscopy is considered the most accurate screening tool for colorectal neoplasm, the optimal interval of repeating a screening colonoscopy, particularly in average-risk subjects after a negative colonoscopy, is poorly defined. We determine the 5-year risk of advanced neoplasia on rescreening colonoscopy in a cohort of average-risk Chinese subjects.
  
  
  METHODS
  We invited a cohort of asymptomatic average-risk Chinese subjects (aged 55-75 years) who were recruited in our previous screening colonoscopy studies to undergo a repeat colonoscopy at the end of 5 years. The rates of advanced colorectal neoplasia at the end of 5 years in these subjects were determined according to their baseline colonoscopy findings.
  
  
  RESULTS
  A total of 511 of the 620 eligible subjects underwent repeat-screening colonoscopy at the end of 5 years. Among them, 401 subjects had no baseline neoplasia (370 with no baseline polyps and 31 with hyperplastic polyps). In subjects with no baseline polyp, 24.6% were found to have at least one adenoma and 1.4% had advanced neoplasia on rescreening. The number needed to rescreen for one advanced neoplasia in subjects with no baseline polyp was 74 (95% confidence interval (CI), 32-168). The prevalence of advanced neoplasia at 5 years in subjects with baseline-advanced neoplasia was 20.7% (relative risk 19.6; 95% CI, 5.2-74.1; vs. subjects with no baseline polyp). The presence of baseline-advanced neoplasia (odds ratio (OR) 13.1; 95% CI, 4.1-41.7) and age in years (OR 1.11; 95% CI, 1.01-1.22) are two independent factors for development of advanced neoplasia at 5 years.
  
  
  CONCLUSIONS
  The risk of advanced neoplasia is sufficiently low 5 years after a normal screening colonoscopy in Chinese subjects.
authors.affiliation: Institute of Digestive Disease, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. dr_wkleung@alumni.cuhk.net
authors.forename: Wai K
authors.initials: WK
authors.lastname: Leung
authors.forename: James Yw
authors.initials: JY
authors.lastname: Lau
authors.forename: Bing Yee
authors.initials: BY
authors.lastname: Suen
authors.forename: Grace Lh
authors.initials: GL
authors.lastname: Wong
authors.forename: Dorothy Kl
authors.initials: DK
authors.lastname: Chow
authors.forename: Larry H
authors.initials: LH
authors.lastname: Lai
authors.forename: Ka-Fai
authors.initials: KF
authors.lastname: To
authors.forename: Carmen Km
authors.initials: CK
authors.lastname: Yim
authors.forename: Envy Sf
authors.initials: ES
authors.lastname: Lee
authors.forename: Kelvin Kf
authors.initials: KK
authors.lastname: Tsoi
authors.forename: Simon Sm
authors.initials: SS
authors.lastname: Ng
authors.forename: Joseph Jy
authors.initials: JJ
authors.lastname: Sung
mesh_terms: D000368:Aged; D002681:China; D003113:Colonoscopy / Q000706:statistics & numerical data*; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors