What are the guidelines for colonoscopy (colon examination using a flexible tube with a camera) screening for colorectal (colon and rectal) cancer?

Colorectal Cancer Screening Guidelines

For average-risk individuals, colorectal cancer screening should begin at age 45 and continue through age 75, with colonoscopy every 10 years or annual fecal immunochemical test (FIT) as the preferred first-tier screening options. 1

Risk Stratification

Average Risk (70-80% of cases)

• Starting age: 45 years 1
• Screening options:
  • First-tier options (preferred):
    • Colonoscopy every 10 years
    • Annual FIT
  • Second-tier options:
    • CT colonography every 5 years
    • FIT-fecal DNA (Cologuard) every 3 years
    • Flexible sigmoidoscopy every 5 years 1, 2

Moderate Risk (15-20% of cases)

• History of adenomatous polyps:
  • Total colon examination within 3 years after initial polyp removal
  • If normal, repeat every 5 years 3
• Family history of colorectal cancer or advanced adenoma:
  • One first-degree relative diagnosed before age 60 or two first-degree relatives at any age:
    • Begin screening at age 40 or 10 years before youngest case in family (whichever is earlier)
    • Colonoscopy every 5 years 1, 4
  • Single first-degree relative diagnosed at ≥60 years:
    • Begin screening at age 40
    • Follow average-risk screening intervals 2

High Risk (5-10% of cases)

• Familial Adenomatous Polyposis (FAP):
  • Begin endoscopic surveillance at puberty
  • Consider genetic testing and colectomy if positive 3
• Hereditary Non-Polyposis Colorectal Cancer (HNPCC/Lynch Syndrome):
  • Begin colonoscopy at age 25
  • Repeat every 1-2 years 4
• Inflammatory Bowel Disease:
  • Begin colonoscopy 8 years after onset of pancolitis or 12-15 years after onset of left-sided colitis
  • Repeat every 1-2 years 3, 4

Special Populations

• African Americans: Higher incidence and mortality rates (43.6 vs. 37.8 cases per 100,000 in White adults)
  • Begin screening at age 45 (some guidelines suggest age 40) 1
• Smokers with ≥20 pack-year history: Considered higher risk 1

When to Stop Screening

• Age 75: Stop routine screening for average-risk adults who are up-to-date with prior screening 1, 5
• Ages 76-85: Individualize decision based on prior screening history, overall health, and life expectancy 1
• After age 85: Discontinue screening 1
• Life expectancy <10 years: Discontinue screening 3, 5

Follow-up of Abnormal Findings

• Adenomatous polyps: Follow-up colonoscopy in 3-5 years, depending on size and number of polyps 1
• Positive stool-based test: Follow-up with timely diagnostic colonoscopy 1

Common Pitfalls to Avoid

1. Neglecting follow-up: Any positive stool-based test requires follow-up colonoscopy
2. Overscreening: Continuing screening beyond age 75 in average-risk individuals with prior negative screenings
3. Underscreening: Missing higher-risk individuals who need earlier or more frequent screening
4. Inadequate risk assessment: Failing to identify family history or other risk factors that would modify screening approach
5. Relying solely on flexible sigmoidoscopy: Up to 38% of neoplastic polyps would be missed in the absence of distal findings 6

Colonoscopy remains the gold standard for screening as it allows for direct visualization and removal of precancerous lesions during the same procedure. However, patient preferences, test availability, and adherence considerations should guide the selection of screening modality to ensure regular screening occurs.