When should I undergo colonoscopy screening for colorectal cancer?

When to Get Colonoscopy Screening

For average-risk adults, begin colorectal cancer screening at age 50 years with colonoscopy every 10 years or annual fecal immunochemical testing (FIT), and continue screening through age 75. 1, 2

Starting Age by Risk Category

Average-Risk Adults

• Age 50 is the evidence-based starting point supported by decades of randomized controlled trials demonstrating mortality reduction (strong recommendation, high-quality evidence). 1, 3

• Age 45 may be considered based on rising colorectal cancer incidence in younger adults, but this carries only a qualified/weak recommendation due to limited outcome data—it relies on epidemiologic modeling rather than direct trial evidence. 1, 2, 3

• Prioritize age 50 screening when resources are limited, offering age 45 screening when feasible, particularly for patients expressing concern about their risk. 3

High-Risk Adults with Family History

• Start at age 40 OR 10 years before the youngest affected first-degree relative's diagnosis (whichever comes first) if you have one first-degree relative with colorectal cancer or advanced adenoma diagnosed before age 60, or two first-degree relatives diagnosed at any age. 1, 2

• Screen every 5 years with colonoscopy in this high-risk group. 1, 2

• Start at age 40 with average-risk screening options (colonoscopy every 10 years or annual FIT) if your first-degree relative was diagnosed at age 60 or older. 2, 3

• Verify the exact age at diagnosis of affected relatives—the 60-year cutoff determines whether 5-year or 10-year intervals apply. 2

African Americans

• Consider starting at age 45 due to higher colorectal cancer incidence in this population, though evidence quality is limited. 1

Screening Test Options

First-Tier (Preferred)

• Colonoscopy every 10 years: Allows simultaneous detection and removal of polyps; gold standard for prevention. 1, 2, 3

• Annual FIT: Equally ranked first-tier option, particularly useful in organized population-based programs. 1, 2, 3

Second-Tier (If First-Tier Declined)

• CT colonography every 5 years: Acceptable alternative but involves radiation exposure. 1, 2, 3

• Multitarget stool DNA (FIT-DNA) every 3 years: Reasonable option for those refusing colonoscopy and FIT. 1, 2, 3

• Flexible sigmoidoscopy every 5-10 years: Examines only the distal colon, missing proximal lesions. 1, 2, 3

Critical caveat: Any positive non-colonoscopy test MUST be followed by timely diagnostic colonoscopy. 2, 3

When to Stop Screening

Age 75

• Stop routine screening if you are up-to-date with prior negative tests, especially if you had a recent high-quality colonoscopy. 1, 2, 3

• Stop if life expectancy is less than 10 years regardless of prior screening history. 1, 4

Ages 76-85

• Screen only those never previously screened, after assessing overall health, comorbidities, and ability to tolerate treatment if cancer were detected. 1, 2, 3

• Do not offer routine screening to those already up-to-date with prior negative tests. 1, 3

Age 86 and Older

• Discontinue all screening regardless of prior history—harms outweigh benefits at this age. 1, 2, 3

Common Pitfalls to Avoid

• Do not delay evaluation of symptomatic patients (rectal bleeding, unexplained anemia, change in bowel habits) regardless of age—these require diagnostic colonoscopy, not screening. 3

• Do not continue screening beyond age 85 when evidence clearly shows harms exceed benefits. 1, 3

• Do not assume all family history carries the same risk—document whether relatives had cancer or advanced adenomas, and their exact age at diagnosis, as this determines screening intensity. 1, 2

• Do not use colonoscopy as a screening test in patients with inflammatory bowel disease or hereditary cancer syndromes (Lynch syndrome, familial adenomatous polyposis)—these require dedicated surveillance protocols separate from general screening recommendations. 1, 3

Quality Considerations

• Ensure adequate bowel preparation using split-dose regimens, which are superior to single-dose preparations for lesion detection. 5

• Verify your endoscopist achieves cecal intubation rates >95% and adenoma detection rates >25% in men and >15% in women. 5

• Confirm adequate withdrawal time (minimum 6 minutes) to optimize polyp detection. 5