Bowel Cancer Screening: Colonoscopy or Stool Test?

The question sits at the heart of a long-running debate in cancer medicine. Should a 46-year-old man with no particular risk factors for bowel cancer (colorectal cancer) go straight for a colonoscopy — a camera examination of the large bowel — or start with a stool-based test, which checks a sample for hidden traces of blood or abnormal DNA?

The New England Journal of Medicine posted the question to its global readership, presenting a clinical case vignette alongside the two options and inviting doctors to vote on their preferred approach.

Both methods are accepted screening tools. A colonoscopy allows a doctor to examine the bowel directly and remove any suspicious growths (polyps) during the same procedure. Stool-based tests are less invasive and can be done at home, but a positive result does require a follow-up colonoscopy to investigate further.

The NHS in England currently offers bowel cancer screening to everyone aged 50 to 74 through a home stool test called the faecal immunochemical test (FIT). People at higher risk may be referred for colonoscopy earlier. The American Cancer Society lowered its recommended starting age for average-risk screening to 45 in 2018, which is why the journal’s case of a 46-year-old is chiefly relevant to ongoing international policy discussions.

Bowel cancer is the fourth most common cancer in the UK, according to the NHS, and the second biggest cause of cancer death. Catching it early, before symptoms appear, markedly improves survival rates.

Key information

• If you are aged 50 to 74, you should receive an NHS bowel cancer screening kit by post automatically
• If you have symptoms such as blood in your stool, a change in bowel habit lasting more than three weeks, or unexplained weight loss, contact your GP — do not wait for a screening invitation
• For general health queries, call NHS 111