title: Long-term colorectal-cancer incidence and mortality after lower endoscopy.
abstract: BACKGROUND
  Colonoscopy and sigmoidoscopy provide protection against colorectal cancer, but the magnitude and duration of protection, particularly against cancer of the proximal colon, remain uncertain.
  
  
  METHODS
  We examined the association of the use of lower endoscopy (updated biennially from 1988 through 2008) with colorectal-cancer incidence (through June 2010) and colorectal-cancer mortality (through June 2012) among participants in the Nurses' Health Study and the Health Professionals Follow-up Study.
  
  
  RESULTS
  Among 88,902 participants followed over a period of 22 years, we documented 1815 incident colorectal cancers and 474 deaths from colorectal cancer. With endoscopy as compared with no endoscopy, multivariate hazard ratios for colorectal cancer were 0.57 (95% confidence interval [CI], 0.45 to 0.72) after polypectomy, 0.60 (95% CI, 0.53 to 0.68) after negative sigmoidoscopy, and 0.44 (95% CI, 0.38 to 0.52) after negative colonoscopy. Negative colonoscopy was associated with a reduced incidence of proximal colon cancer (multivariate hazard ratio, 0.73; 95% CI, 0.57 to 0.92). Multivariate hazard ratios for death from colorectal cancer were 0.59 (95% CI, 0.45 to 0.76) after screening sigmoidoscopy and 0.32 (95% CI, 0.24 to 0.45) after screening colonoscopy. Reduced mortality from proximal colon cancer was observed after screening colonoscopy (multivariate hazard ratio, 0.47; 95% CI, 0.29 to 0.76) but not after sigmoidoscopy. As compared with colorectal cancers diagnosed in patients more than 5 years after colonoscopy or without any prior endoscopy, those diagnosed in patients within 5 years after colonoscopy were more likely to be characterized by the CpG island methylator phenotype (CIMP) (multivariate odds ratio, 2.19; 95% CI, 1.14 to 4.21) and microsatellite instability (multivariate odds ratio, 2.10; 95% CI, 1.10 to 4.02).
  
  
  CONCLUSIONS
  Colonoscopy and sigmoidoscopy were associated with a reduced incidence of cancer of the distal colorectum; colonoscopy was also associated with a modest reduction in the incidence of proximal colon cancer. Screening colonoscopy and sigmoidoscopy were associated with reduced colorectal-cancer mortality; only colonoscopy was associated with reduced mortality from proximal colon cancer. Colorectal cancer diagnosed within 5 years after colonoscopy was more likely than cancer diagnosed after that period or without prior endoscopy to have CIMP and microsatellite instability. (Funded by the National Institutes of Health and others.).
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA.
authors.forename: Reiko
authors.initials: R
authors.lastname: Nishihara
authors.forename: Kana
authors.initials: K
authors.lastname: Wu
authors.forename: Paul
authors.initials: P
authors.lastname: Lochhead
authors.forename: Teppei
authors.initials: T
authors.lastname: Morikawa
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Liao
authors.forename: Zhi Rong
authors.initials: ZR
authors.lastname: Qian
authors.forename: Kentaro
authors.initials: K
authors.lastname: Inamura
authors.forename: Sun A
authors.initials: SA
authors.lastname: Kim
authors.forename: Aya
authors.initials: A
authors.lastname: Kuchiba
authors.forename: Mai
authors.initials: M
authors.lastname: Yamauchi
authors.forename: Yu
authors.initials: Y
authors.lastname: Imamura
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Rosner
authors.forename: Charles S
authors.initials: CS
authors.lastname: Fuchs
authors.forename: Edward
authors.initials: E
authors.lastname: Giovannucci
authors.forename: Shuji
authors.initials: S
authors.lastname: Ogino
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Chan
mesh_terms: D000236:Adenoma / Q000175:diagnosis / Q000453:epidemiology / Q000401:mortality / Q000517:prevention & control; D000368:Aged; D015331:Cohort Studies; D003111:Colonic Polyps / Q000235:genetics / Q000473:pathology; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality / Q000517:prevention & control; D004273:DNA, Neoplasm / Q000032:analysis; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D015999:Multivariate Analysis; D009154:Mutation; D012812:Sigmoidoscopy; D014481:United States / Q000453:epidemiology
chemical_list: D004273:DNA, Neoplasm
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