Colorectal Cancer Screening Guidelines
The American Cancer Society recommends that adults aged 45 years and older with average risk of colorectal cancer undergo regular screening with either a high-sensitivity stool-based test or a structural (visual) examination, depending on patient preference and test availability. 1
Risk Assessment and Starting Age
Average-Risk Individuals:
- Begin screening at age 45 years (qualified recommendation by ACS) 1
- Strong recommendation for screening at age 50 years and older 1
- Continue screening through age 75 years for those in good health with life expectancy >10 years 1
High-Risk Individuals:
- Begin screening at age 40 years or 10 years younger than the age at which the youngest affected relative was diagnosed with colorectal cancer 1, 2
- African Americans should begin screening at age 45 years due to higher incidence and mortality rates 1, 2
- For individuals with first-degree relatives with colorectal cancer diagnosed before age 45, screening should begin 16 years earlier than the general population 3
Recommended Screening Methods
Stool-Based Tests:
- Fecal immunochemical test (FIT) annually 1, 2
- High-sensitivity guaiac-based fecal occult blood test (gFOBT) annually 1, 2
- Multitarget stool DNA test every 3 years 1, 2
Structural (Visual) Examinations:
- Colonoscopy every 10 years 1, 2
- CT colonography every 5 years 1, 2
- Flexible sigmoidoscopy every 5 years 1, 2
Test Selection Considerations
Colonoscopy is considered the gold standard diagnostic test due to its high sensitivity and specificity for detecting colorectal cancer and precancerous lesions 2. It is particularly recommended for high-risk individuals 1.
For average-risk individuals, test selection should be based on:
- Benefits and harms of the screening test
- Test availability
- Patient preferences 1
All positive results on non-colonoscopy screening tests must be followed up with timely colonoscopy 1.
When to Stop Screening
- Age 75 years for average-risk adults in good health 1
- For adults aged 76-85 years, individualize decisions based on:
- Patient preferences
- Life expectancy
- Health status
- Prior screening history 1
- Screening is discouraged for individuals older than 85 years 1, 2
Screening Intervals for High-Risk Groups
The optimal screening strategy varies considerably with family history:
- For individuals with 1 first-degree relative diagnosed after age 50: colonoscopy every 5 years 4
- For individuals with 1 first-degree relative diagnosed before age 50: colonoscopy every 4 years 4
- For individuals with 2 or more first-degree relatives diagnosed after age 50: colonoscopy every 3 years 4
- For individuals with 2 or more first-degree relatives with at least 1 diagnosed before age 50: colonoscopy every 3 years 4
Common Pitfalls and Caveats
- Inadequate bowel preparation significantly reduces diagnostic accuracy of colonoscopy 2
- Incomplete colonoscopy (failure to reach the cecum) misses proximal lesions 2
- Colonoscopy carries small risks of perforation (0.1-0.2%) and bleeding, particularly after polyp removal 2
- Non-adherence to recommended screening intervals reduces effectiveness of screening programs 5
- Failure to follow up positive stool-based tests with colonoscopy negates the benefits of screening 1
The most recent evidence strongly supports beginning colorectal cancer screening at age 45 for average-risk individuals, with the specific test selection based on individual factors and preferences, while ensuring appropriate follow-up of any positive screening results.