Colorectal Cancer Screening in Primary Care: Who, When, and How

Colorectal cancer screening saves lives, and a lot of it runs through primary care. For most adults, screening begins at age 45 and continues through 75. After that, decisions get individualized.

Who should be screened

• Age 45 to 75: screen everyone.
• Age 76 to 85: individualize based on health, prior screening, and patient preferences.
• Over 85: screening is generally not recommended.

Average vs increased risk

Average risk:

• No personal history of adenomas, polyps, or colorectal cancer.
• No first-degree relative with colorectal cancer or advanced adenoma.
• No hereditary syndrome such as Lynch or FAP.
• No inflammatory bowel disease with colitis (ulcerative colitis, Crohn's colitis).

Increased risk, which means colonoscopy:

• Personal history of colorectal cancer or adenomas.
• First-degree relative with colorectal cancer or advanced adenoma, especially under 60, or two or more relatives at any age.
• Hereditary syndromes (Lynch, FAP, and others).
• Inflammatory bowel disease with extensive colitis.

For increased-risk patients, timing is often: start at 40, or 10 years earlier than the youngest affected relative, and repeat about every 5 years. GI will guide the exact interval.

Test options and intervals (average risk)

A note on FOBT: traditional guaiac FOBT is less specific. If you use it, it should be high-sensitivity gFOBT annually. Most clinics prefer FIT over FOBT.

Quick picks (average risk)

• Wants at-home and lowest cost: FIT yearly.
• At-home but more sensitive: FIT-DNA (Cologuard) every 1 to 3 years.
• One and done for a decade, with polyp removal: colonoscopy every 10 years.

Important: a positive stool test means a diagnostic colonoscopy. Do not repeat the stool test.

After colonoscopy

• Normal: typically every 10 years.
• Polyps found: surveillance is usually every 3 to 5 years, depending on number, size, and histology. GI sets the interval.

Who should not get stool-only screening

• High-risk patients (see above): colonoscopy only.
• Symptomatic patients (bleeding, iron-deficiency anemia, weight loss, change in bowel habits): this is diagnostic, not screening. Refer for colonoscopy.

Prep and practical tips

• Colonoscopy prep: clear-liquid diet the day before plus bowel prep. Arrange a driver.
• Insurance: a screening colonoscopy is usually covered. A colonoscopy after a positive stool test may be billed as diagnostic, so prepare patients for a possible cost difference.
• Medication review: anticoagulants and antiplatelets. Coordinate with GI if polypectomy is likely.

Pearls that save time

• The best test is the one your patient will actually complete. Offer a choice.
• A positive stool test does not mean repeat the stool test. Go straight to colonoscopy.
• High-risk or symptomatic patients skip stool tests and go to colonoscopy.
• Document family history details (which relative, age at diagnosis) so you set the right pathway.

Frequently asked questions

A patient's FIT came back positive. Do I repeat it?
No. A positive stool test goes to a diagnostic colonoscopy. Repeating the stool test only delays the diagnosis.

Can a high-risk patient use Cologuard or FIT?
No. Increased-risk patients need colonoscopy. Stool-based tests are for average-risk screening only.

My patient has rectal bleeding. Is that a screening situation?
No. Symptoms make it diagnostic, not screening. Refer for colonoscopy rather than ordering a stool test.

Colorectal cancer screening gets simpler once you sort average risk from increased risk and remember that a positive stool test always means colonoscopy. It sits alongside the other adult prevention workflows like AAA screening. If you want the test intervals on one page in clinic, the Clinical Desk Reference ($37 quick-reference) keeps them handy, and the Primary Care Clinical Mastery Program (AANP-accredited) walks through the everyday decisions in more depth.

Education only. Use clinical judgment and your local guidelines.

Written by Allison Sowders, MSN, APRN, FNP-BC, a practicing primary care nurse practitioner and founder of Nurse Practitioner Mentor. Reviewed July 2026.