Colorectal cancer screening begins at age 45 for average-risk adults, per the US Preventive Services Task Force's 2021 statement, which lowered the starting age from 50 and issued a B recommendation for screening everyone from 45 through 75. The statement accepts six testing strategies — stool tests at home, sigmoidoscopy, colonoscopy, and CT colonography among them — and its modeling found the strategies offer comparable life-years gained when completed on schedule.
This site publishes information, not medical advice. The ages, intervals and grades below belong to the named task force and the cited agencies, and they apply to adults at average risk; people with a family history of colorectal cancer, inflammatory bowel disease, or certain inherited syndromes follow different, often earlier schedules set with their own clinician.
Why did the starting age drop from 50 to 45?
The task force lowered the age in response to decades of rising colorectal cancer incidence in adults under 50. Its 2021 statement, published in JAMA, cites analyses from the American Cancer Society and the National Cancer Institute's SEER program showing that diagnoses in adults 45 to 49 had increased through the 2010s while rates in older groups fell with screening. The American Cancer Society had already moved its own recommendation to 45 in 2018, and the task force's modeling concluded that starting at 45 added life-years gained at a cost-effectiveness similar to the traditional 50 start. Medicare added coverage of screening for 45-to-49-year-olds following the change, and the task force's A grade continues for adults 50 to 75.
What are the screening options and intervals?
The task force accepts the following strategies, with intervals drawn from its 2021 statement:
- High-sensitivity guaiac fecal occult blood test or fecal immunochemical test — every year.
- sDNA-FIT, the stool DNA test with FIT — every one to three years.
- CT colonography — every five years.
- Flexible sigmoidoscopy — every five years, or every 10 with annual FIT.
- Colonoscopy — every 10 years for average-risk adults with normal results.
The statement does not rank a single best test. Its emphasis is on completion: a stool test done every year protects better in its models than a colonoscopy repeatedly postponed, because the strategies produce similar life-years gained when each is performed on its own schedule.
How the options differ in practice
| Option | Interval | What it involves |
|---|---|---|
| FIT or high-sensitivity FOBT | Annual | Home stool collection, no bowel prep, positive result requires follow-up colonoscopy |
| sDNA-FIT | Every 1 to 3 years | Home stool test adding DNA markers; positive results require colonoscopy |
| CT colonography | Every 5 years | Bowel prep and imaging; abnormalities require colonoscopy |
| Flexible sigmoidoscopy | Every 5 years | Bowel prep, partial-scope examination; findings often require colonoscopy |
| Colonoscopy | Every 10 years | Full bowel prep and sedation; polyps can be removed during the procedure |
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What happens after an abnormal stool test?
Every non-colonoscopy strategy is a two-step pathway: an abnormal or positive result is not a cancer diagnosis, but it does require a follow-up colonoscopy to examine the colon directly and remove polyps. The task force's models account for this — the benefits of stool testing depend on completing the second step, which is why programs that mail kits and follow up by phone report higher completion than programs that merely hand out kits. Missing the follow-up colonoscopy forfeits most of the test's protective value.
What are the numbers on colorectal cancer itself?
Per American Cancer Society estimates published before its 2026 report cycle, colorectal cancer is among the leading causes of cancer death in the United States, with lifetime risk in the United States roughly one in 23 for men and one in 25 for women. Deaths have declined over recent decades in screened age groups, an trend the task force and the cancer society attribute in part to screening removing precancerous polyps. Incidence in adults under 55, by contrast, has risen about 1 percent to 2 percent annually since the mid-1990s, per SEER program analyses — the trend behind the age change.
When to talk to a clinician
Screening intervals do not apply to symptoms. Blood in the stool, a persistent change in bowel habits, unexplained weight loss, iron-deficiency anemia, or ongoing abdominal pain warrant clinical evaluation at any age rather than waiting for a scheduled test. People with a first-degree relative diagnosed with colorectal cancer or advanced polyps, a personal history of inflammatory bowel disease, or a known hereditary syndrome should ask a clinician when to start — commonly earlier than 45 — and which interval applies to them. Adults 76 to 85 fall under a separate task force statement, with screening decided case by case on prior screening history and health status.
The task force's message is less about which test than about which date: start at 45, follow the interval for whatever test is chosen, and finish the follow-up colonoscopy if a stool test comes back positive.