Bowel cancer screening looks for early cancer and polyps in people who have no symptoms. Most people at average risk should be screened from age 45 to 75. A home stool test (FIT) and colonoscopy are both good choices; what matters most is being screened regularly. Symptoms such as bleeding are not a reason to wait for screening: see a doctor, at any age.

Why screen?

Bowel cancer usually develops slowly, over many years, from a polyp. Screening finds polyps, which can be removed before they become cancer, and finds cancer at an early stage, when it is usually curable. Regular screening lowers the chance of dying from bowel cancer.

Early bowel cancer often causes no symptoms, which is why screening is offered to people who feel well.

Who should be screened?

• Men and women at average risk: from age 45 to 75
• From 76 to 85: decided individually, depending on your health and previous screening
• Over 85: screening is not usually recommended

Average risk means no symptoms, no personal history of polyps, bowel cancer or inflammatory bowel disease, and no strong family history. Bowel cancer has become more common in adults under 50 in many countries, which is why American guidelines lowered the starting age from 50 to 45. Some programmes still start at 50: follow the screening programme available where you live, or ask your doctor.

Screening tests

Several tests are effective. The best test is the one you will actually do, and repeat when it is due:

• Faecal immunochemical test (FIT): a simple home stool test for tiny amounts of blood, repeated every year (American guidance) or every 2 years (many other programmes). No diet changes or bowel preparation are needed
• Colonoscopy: a camera examines the whole large bowel, and polyps are removed at the same time. If it is normal and of good quality, it is usually repeated after 10 years. It needs bowel preparation and usually sedation
• Other options in some countries: a stool DNA test (usually every 3 years), CT colonography or flexible sigmoidoscopy (every 5 years)

Newer blood tests are available in some countries, but they miss most polyps and some cancers, and are not recommended in place of a stool test or colonoscopy.

If your stool test is positive

A positive FIT means that blood was found, not that you have cancer. Most positive results are not caused by cancer: common causes are polyps or piles, and sometimes no cause is found. You do need a colonoscopy to find the cause, and it should be done promptly, ideally within weeks rather than months. Do not repeat the stool test instead: a negative second test does not cancel a positive one.

Higher risk: earlier or more frequent checks

Some people need colonoscopy rather than a stool test, often starting earlier:

• A close relative (parent, brother, sister or child) with bowel cancer or an advanced polyp: usually starting at age 40, or 10 years before the age at which your youngest affected relative was diagnosed, whichever comes first. If one relative was diagnosed at 60 or older, a stool test or colonoscopy at the usual intervals may be enough. If a relative was diagnosed under 60, or two or more are affected, colonoscopy is usually repeated every 5 years
• Inherited conditions such as Lynch syndrome or familial adenomatous polyposis (FAP): colonoscopy starts much younger and is repeated much more often; see the separate leaflets
• Ulcerative colitis or Crohn's disease affecting the colon: surveillance colonoscopy usually starts about 8 years after symptoms began, or from diagnosis if you also have primary sclerosing cholangitis. Your IBD team will advise on timing
• Previous bowel cancer or polyps: follow the surveillance plan your doctor gave you, rather than routine screening

If you are not sure which group you are in, ask your doctor before choosing a test.

Symptoms are not screening

Screening is for people who feel well. If you have symptoms, do not wait for a screening test, and do not rely on a previous normal stool test. See a doctor promptly, at any age, if you have:

• Blood in or on the stool
• A change in bowel habit lasting more than a few weeks
• Unexplained weight loss or iron-deficiency anaemia
• Persistent abdominal pain or a lump in the abdomen

Common questions

This leaflet is general information and does not replace advice from your own doctor. Version 1.0, October 2026. Next review October 2028.