Colonoscopic screening of an average-risk population for colorectal neoplasia

Endoscopy. 2009 Jun;41(6):516-21. doi: 10.1055/s-0029-1214757. Epub 2009 Jun 16.


Background and study aims: The role of screening colonoscopy in an asymptomatic, average-risk population remains to be determined. Moreover, the value of screening colonoscopy in individuals older than 75 years and for right-sided lesions has recently been questioned. The aims were to assess: (i) the risk of colorectal neoplasia in a large consecutively screened asymptomatic average-risk population, aged 40-85 years; (ii) whether colonoscopy is better than sigmoidoscopy for primary screening; and (iii) the prevalence of right-sided lesions at different ages.

Patients and methods: This prospective study, analyzed data from 1563 consecutive, asymptomatic, average-risk individuals, aged 40-85 years, who underwent screening colonoscopy.

Results: Overall, neoplastic lesions were detected in 262 individuals (17% of the study population), of whom 75 had advanced lesions (5% of population) and nine had colorectal cancers (CRC) (0.6% of population). The prevalence of all lesions increased with age, with the highest percentages in the > 75 age group (26.5% with neoplastic and 6 % with advanced lesions). Higher age was also associated with relatively more right-sided lesions. In particular the prevalence of proximal neoplasia, without concurrent distal neoplasia, increased from 5% in those < 50 years to 24% in those > 75 years. Those with distal lesions had a higher overall risk for proximal lesions (odds ratio [OR] 3.2); nevertheless flexible sigmoidoscopy alone would have missed up to 40% of all lesions and up to 3.5% of advanced neoplastic lesions in this patient subgroup.

Conclusions: Screening colonoscopy in asymptomatic, average-risk individuals is mandatory, as noteworthy numbers of advanced colorectal neoplasias have been detected in all age groups, especially in those aged > 75. Most importantly, many of the detected lesions were proximal and would not be revealed by sigmoidoscopy alone.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Aged
  • Colonoscopy
  • Colorectal Neoplasms / diagnosis*
  • Colorectal Neoplasms / epidemiology*
  • Female
  • Humans
  • Male
  • Mass Screening
  • Middle Aged
  • Prevalence
  • Risk Factors
  • Sigmoidoscopy