At what age should average risk individuals start colonoscopy (colon cancer screening) screening?

Colorectal Cancer Screening for Average-Risk Individuals

Colorectal cancer screening should begin at age 45 for all average-risk individuals. 1

Current Recommendations

The most recent guidelines from major professional societies have updated their recommendations for when to begin colorectal cancer screening in average-risk individuals:

• U.S. Multi-Society Task Force (MSTF) 2021: Suggests offering CRC screening to all average-risk individuals age 45-49 (weak recommendation; low-quality evidence) and recommends screening for all average-risk individuals beginning at age 50 (strong recommendation, high-quality evidence) 1

• United States Preventive Services Task Force (USPSTF) 2021: Recommends screening for colorectal cancer in adults aged 45 to 49 years (Grade B recommendation) and in adults aged 50 to 75 years (Grade A recommendation) 1

• American Cancer Society (ACS) 2018: Recommends that adults aged 45 and older with average risk undergo regular screening 1

Rationale for Starting at Age 45

The recommendation to begin screening at age 45 is based on several important factors:

• Increasing CRC incidence in younger adults: Incidence rates for 45-49 year-olds now match incidence in populations that were previously eligible for screening 1

• Similar disease biology: Molecular studies show that tumors in 40-49 year-olds have similar biology to those in individuals over 50 1

• Comparable yield of screening: Data show that the rate of advanced colorectal neoplasia in average-risk individuals ages 45-49 is similar to rates observed in screening cohorts of those ages 50-59 1

• Positive modeling studies: Previous modeling studies demonstrate that benefits of screening outweigh harms in average-risk 45-49 year-olds, with acceptable cost-effectiveness 1

When to Stop Screening

Screening should continue until:

• Age 75 for most individuals who are up to date with screening and have negative prior screening tests 1

• For individuals aged 76-85, screening should be individualized based on:

  • Prior screening history
  • Life expectancy
  • Overall health status
  • Patient preferences 1

• Do not screen individuals age 86 and older: Overall mortality risk and risk of adverse events associated with colonoscopy outweigh the life expectancy benefits 1

Special Considerations for Family History

For individuals with a family history of colorectal cancer:

• First-degree relative diagnosed at age ≥60: Begin screening at age 40 with standard average-risk screening options 1, 2

• First-degree relative diagnosed at age <60 or two first-degree relatives with CRC: Begin colonoscopy screening at age 40 or 10 years before the earliest diagnosis in the relative, whichever comes first, and repeat every 5 years 1, 2

• First-degree relative with documented advanced adenoma: Follow the same recommendations as for those with a first-degree relative with CRC 2

Common Pitfalls and Caveats

1. Failure to recognize increased risk in younger patients: CRC incidence is rising in persons under age 50, so thorough evaluation of young persons with suspected colorectal bleeding is essential 3

2. Overscreening elderly patients: For individuals over 75 who have had negative prior screenings, the risks of colonoscopy may outweigh the benefits 1

3. Missing advanced neoplasia with limited screening methods: In studies of asymptomatic 50-59 year-olds, flexible sigmoidoscopy would have missed up to 38% of polyps found on colonoscopy 4

4. Inadequate follow-up of positive non-colonoscopy screening tests: All positive results on non-colonoscopy screening tests should be followed up with timely colonoscopy 1

5. Poor compliance in high-risk groups: Special efforts should be made to ensure screening compliance in younger individuals with a family history of CRC 1

By following these evidence-based recommendations, clinicians can optimize colorectal cancer prevention and early detection, ultimately reducing CRC morbidity and mortality.