title: Subsite-specific colorectal cancer risk in the colorectal endoscopy era.
abstract: BACKGROUND
  Colorectal endoscopy (sigmoidoscopy and colonoscopy) is thought to reduce colorectal cancer (CRC) risk. Since the 1980s, its use has increased in the United States, which may be a reason for decreasing CRC incidence rates.
  
  
  OBJECTIVE
  To investigate the plausibility of a contribution of colorectal endoscopy use to the decrease in CRC risk.
  
  
  METHODS
  Descriptive analysis of temporal trends.
  
  
  METHODS
  U.S. population from 1978 to 2007.
  
  
  METHODS
  Using incidence data from the Surveillance, Epidemiology and End Results Program, we assessed the subsite-specific cumulative risk of CRC developing until age 79 years.
  
  
  RESULTS
  The cumulative risk of proximal CRC remained relatively stable over the observation period, varying between 2.09% (95% CI, 2.06%-2.11%) and 2.66% (95% CI,2.62%-2.69%) for men and between 1.90% (95% CI, 1.88%-1.93%) and 2.24% (95% CI, 2.21%-2.27%) for women. By contrast, the cumulative risk of distal CRC decreased from 4.68% (95% CI, 4.64%-4.73%) to 3.03% (95% CI, 3.00%-3.06%) for men and from 3.15% (95% CI, 3.11%-3.18%) to 1.93% (95% CI, 1.91%-1.95%) for women, which was largely attributable to the reduced cumulative risk of cancer in the sigmoid colon. The observed pattern was restricted to the population aged 50 to 79 years, whereas the magnitude of the decrease was greater for older age groups and similar across stages.
  
  
  CONCLUSIONS
  The study is based on aggregated registry data only; therefore, no inferences about causal effects can be drawn.
  
  
  CONCLUSIONS
  The results show a major reduction of CRC risk, particularly in the sigmoid colon. Increased use of colorectal endoscopy in the population aged 50 years and older along with environmental factors may have contributed to the decreasing risk.
authors.affiliation: Division of Clinical Epidemiology and Aging Research, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Stock
authors.forename: Dianne
authors.initials: D
authors.lastname: Pulte
authors.forename: Ulrike
authors.initials: U
authors.lastname: Haug
authors.forename: Hermann
authors.initials: H
authors.lastname: Brenner
mesh_terms: D000368:Aged; D003113:Colonoscopy / Q000706:statistics & numerical data*; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors