What are the guidelines for colonoscopy screening?

Colorectal Cancer Screening Guidelines

Colorectal cancer screening should begin at age 45 for average-risk individuals, continue through age 75, and include colonoscopy every 10 years or annual FIT as first-tier screening options. 1, 2

Screening Age Recommendations

When to Start Screening:

• Average-risk individuals: 45 years 1, 3
• African Americans: 45 years (some guidelines recommend 40 years) 3, 1
• Family history of CRC or advanced adenoma:
  • One first-degree relative diagnosed <60 years or two first-degree relatives at any age: Begin at 40 years or 10 years before the youngest affected relative's diagnosis, whichever is earlier 2, 4
  • Single first-degree relative diagnosed ≥60 years: Begin at 40 years 2

When to Stop Screening:

• Ages 76-75: Continue screening for those in good health with life expectancy >10 years 1, 2
• Ages 76-85: Individualize decision based on prior screening history, health status, and life expectancy 1
• After age 85: Discontinue screening 1

Recommended Screening Modalities

Tier 1 (Preferred Options):

• Colonoscopy every 10 years
• Fecal Immunochemical Test (FIT) annually

Tier 2 Options:

• CT colonography every 5 years
• FIT-fecal DNA (Cologuard) every 3 years
• Flexible sigmoidoscopy every 5-10 years

Tier 3 Option:

• Capsule colonoscopy every 5 years (limited evidence)

Screening Test Performance

Test	Sensitivity for CRC	Sensitivity for Advanced Precancerous Lesions	Specificity
Cologuard	92.3%	42.4%	86.6%
FIT	73.8%	23.8%	94.9%

Risk-Based Screening Recommendations

High-Risk Individuals:

• Inflammatory bowel disease (ulcerative colitis or Crohn's with colonic involvement):

  • Begin 8-10 years after symptom onset
  • Repeat every 1-3 years 4

• Hereditary nonpolyposis colorectal cancer (HNPCC/Lynch syndrome):

  • Begin at age 25
  • Repeat every 1-2 years 4

• Adenomatous polyposis syndromes:

  • Begin at age 10 or mid-20s depending on syndrome
  • Repeat every 1-2 years 4

• Peutz-Jeghers syndrome:

  • Begin at age 8
  • If normal, repeat at age 18, then every 3 years 4

Follow-Up Recommendations

• Positive stool-based test: Follow up with diagnostic colonoscopy 1
• Adenomatous polyps removed: Follow up with colonoscopy in 3-5 years (depending on size and number) 1
• Normal colonoscopy: Repeat in 10 years for average-risk individuals 1

Clinical Considerations

Test Selection:

• Colonoscopy is most appropriate for individuals with multiple risk factors 1
• Patient preferences should be considered to improve adherence 1
• Digital rectal exam alone is insufficient for screening 1
• Air-contrast barium enema is no longer recommended as a primary screening tool 1

Potential Harms:

• Colonoscopy: Small risk of perforation and bleeding
• CT colonography: Radiation exposure
• Stool-based tests: False positives leading to unnecessary follow-up procedures 1

Common Pitfalls to Avoid

1. Delaying screening: The rising incidence of CRC in persons under 50 necessitates thorough evaluation of young persons with suspected colorectal bleeding 2

2. Missing proximal lesions: Flexible sigmoidoscopy alone would miss up to 38% of polyps in the absence of distal findings 5

3. Inadequate follow-up: Failing to follow up positive stool-based tests with timely colonoscopy 1

4. Overscreening: Continuing screening beyond age 75 in individuals with prior negative screening and limited life expectancy 2

5. Underscreening high-risk groups: African Americans have the highest incidence and mortality rates for CRC compared to other racial/ethnic groups (43.6 vs 37.8 cases per 100,000 in White adults) 1