Most bowel cancers develop slowly from polyps that can be found and removed before they turn into cancer. Screening and acting early on warning symptoms save lives. When found early, bowel cancer is often curable.

What is it?

Colorectal cancer starts in the lining of the colon or rectum. It usually begins as a polyp, a small growth that can become cancerous over several years. Removing polyps during colonoscopy prevents many cancers.

Who is at higher risk?

• Increasing age, especially from the mid-40s onwards
• A close relative (parent, brother, sister or child) with bowel cancer or advanced polyps, especially if diagnosed before 60
• Inherited conditions such as Lynch syndrome or familial adenomatous polyposis
• Long-standing ulcerative colitis or Crohn's colitis
• Previous polyps or bowel cancer
• Lifestyle: high intake of red and processed meat, low fibre, obesity, physical inactivity, smoking, alcohol, and type 2 diabetes

Symptoms not to ignore

Early cancer often causes no symptoms, which is why screening matters. See a doctor promptly if you notice:

• Blood in or on the stool, or dark stools
• A persistent change in bowel habit (looser, more frequent or constipated) for more than a few weeks
• Unexplained weight loss or tiredness
• Iron-deficiency anaemia
• A lump in the abdomen or persistent abdominal pain
• A feeling of incomplete emptying

Screening

Screening looks for early cancer or polyps in people without symptoms. International guidance generally recommends starting at age 45 to 50 for people at average risk; follow the programme available where you live.

• Faecal immunochemical test (FIT): a simple home stool test for hidden blood, repeated every one to two years. A positive result needs a colonoscopy
• Colonoscopy: examines the whole large bowel and removes polyps at the same time. If normal, it is usually repeated after 10 years in average-risk people

People with a family history start earlier: usually at 40, or 10 years before the age at which their youngest affected relative was diagnosed, whichever comes first, and are checked more often (often every 5 years). Your doctor will advise on your schedule.

Prevention

• Eat more fibre: vegetables, fruit, legumes and wholegrains
• Limit red meat and avoid processed meats
• Stay active and keep a healthy weight
• Do not smoke
• Take part in screening when invited or eligible

Treatment

Treatment depends on the stage and may include removal during colonoscopy for very early cancers, surgery, chemotherapy, radiotherapy (especially for rectal cancer) and targeted treatments. Care is planned by a multidisciplinary team.

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.