At what age should a colonoscopy (colon examination) be performed for average-risk individuals?

Colonoscopy Screening for Average-Risk Adults

Average-risk adults should begin colorectal cancer screening at age 50 years, with colonoscopy every 10 years being a first-tier screening option alongside annual fecal immunochemical testing (FIT). 1, 2, 3

Starting Age for Screening

Standard Recommendation: Age 50

• The strongest evidence supports beginning screening at age 50 for average-risk individuals, based on high-quality evidence demonstrating mortality reduction. 1, 2
• All major guidelines consistently recommend age 50 as the standard starting point for average-risk populations. 1

Emerging Recommendation: Age 45

• Some newer guidelines suggest considering screening starting at age 45, though this carries only a weak recommendation based on low-quality evidence. 2
• The rationale for age 45 stems from increasing colorectal cancer incidence in younger adults and data showing similar rates of advanced neoplasia in 45-49 year-olds compared to 50-59 year-olds (3.6% vs 4.2%, p=0.69). 1, 2
• The 2023 American College of Physicians guidance recommends clinicians consider NOT screening adults ages 45-49, emphasizing the uncertainty around benefits and harms in this age group. 4

Clinical Decision Point: For average-risk patients ages 45-49, the evidence remains equivocal. Given the weak recommendation and uncertainty, prioritize age 50 as the standard starting age unless the patient has specific concerns about early-onset disease. 2, 4

High-Risk Populations Requiring Earlier Screening

Family History Criteria

• Begin screening at age 40 OR 10 years before the youngest affected relative's diagnosis (whichever comes first) if: 1, 3

  • One first-degree relative diagnosed with colorectal cancer or advanced adenoma before age 60
  • Two or more first-degree relatives with colorectal cancer or advanced adenoma at any age

• Screen every 5 years with colonoscopy (not 10 years) for these high-risk individuals. 1, 5

Special Population: African Americans

• Consider beginning screening at age 45 due to higher disease burden and incidence rates in this population. 1, 3

Other High-Risk Conditions

• Inflammatory bowel disease, Lynch syndrome, or familial adenomatous polyposis require specialized screening protocols beginning earlier than age 40. 1, 3

Screening Interval for Colonoscopy

• Every 10 years for average-risk individuals with normal colonoscopy results. 1, 2, 5
• Every 5 years for high-risk individuals (family history criteria above). 1, 5

When to Stop Screening

Age 75: Standard Stopping Point

• Discontinue screening at age 75 for individuals who are up-to-date with screening and have had negative prior results, particularly if they had a high-quality colonoscopy. 1, 2, 3
• The average time to prevent one colorectal cancer death is 10.3 years, making screening unlikely to benefit those with life expectancy under 10 years. 1

Ages 76-85: Selective Screening

• Individualize decisions based on: 1, 2
  • Prior screening history (never-screened individuals may still benefit)
  • Overall health status and comorbidities
  • Life expectancy greater than 10 years

Age 86 and Older

• Do not offer screening as harms outweigh benefits in this age group. 2

Alternative Screening Options

If colonoscopy is declined or unavailable, offer these alternatives in order of preference:

First-Tier (Equally Recommended)

• Annual FIT (fecal immunochemical test) 2, 5, 4

Second-Tier Options

• Flexible sigmoidoscopy every 5-10 years (can be combined with FIT every 2 years) 1, 5, 4
• CT colonography every 5 years 1, 5
• FIT-DNA (multitarget stool DNA) every 3 years 1, 5

Tests NOT Recommended

• Do not use Septin9 serum assay, capsule endoscopy, or urine-based screening tests due to insufficient evidence. 1, 5, 4

Critical Pitfalls to Avoid

• Never delay diagnostic evaluation in symptomatic patients regardless of age, especially those with rectal bleeding—these patients require colonoscopy, not screening tests. 1, 2
• Do not screen more frequently than recommended intervals (e.g., colonoscopy more often than every 10 years in average-risk patients)—this increases costs and harms without improving outcomes. 1
• Ensure adequate bowel preparation quality, as poor preparation compromises colonoscopy effectiveness and may require repeat procedures. 1
• Verify colonoscopy quality metrics, particularly adenoma detection rate, as operator skill significantly impacts screening effectiveness. 1, 5
• Do not continue screening beyond age 85 or in patients with life expectancy under 10 years, as harms definitively outweigh benefits. 1, 2