Colorectal cancer screening

Why screen?

The Danish Health Authority's cancer pathway for colorectal cancer (2022) states about 4,000 new cases a year and about 1,800 deaths a year from the two diseases. Risk rises with age and is higher in men than women. The stage at diagnosis matters for prognosis and treatment options, but treatment also depends on tumour factors and your general health.

The Danish Health Authority recommends screening, but the decision is yours. You can decline the invitation or opt out of the programme at any time.

How bowel cancer develops

Cancer in the colon or rectum starts when cells in the bowel lining grow as small outgrowths called polyps. Most polyps are benign, but some slowly turn into cancer over several years. Risk is increased by age, smoking, heavy alcohol use, a low-fibre diet rich in red meat, and inherited forms of bowel cancer. Physical activity and whole-grain foods lower the risk. Bowel cancer can still occur in people without known risk factors.

Who is invited?

All residents aged 50 to 74 are automatically sent a screening invitation every two years. You receive the letter and a stool sample kit by post.

How the stool test works

Screening uses an immunochemical stool test (FIT) that looks for invisible blood in the stool. You take the sample at home following the enclosed instructions and return it to your regional screening unit in the prepaid envelope. The result is sent to you digitally once the sample has been analysed.

What happens after a positive test?

If the screening FIT shows signs of blood, you are invited for a follow-up endoscopic examination of the colon and rectum (colonoscopy). The invitation comes from your regional screening unit, which also gives you the timing. Signs of blood do not necessarily mean cancer – they can also be caused by haemorrhoids, anal fissures or polyps – but they always need further investigation.

Three possible colonoscopy results

• The bowel is normal. The screening unit states in your result when you will next be invited and what else needs following up.
• Polyps are found. They are usually removed during the same procedure and sent for microscopy. Further follow-up depends on the result.
• Cancer is found. You are referred to a cancer fast-track pathway, where the treating department plans the next steps.

Treatment of bowel cancer

Cancer of the colon and rectum is most often treated surgically. The diseased section of bowel is removed, and in some cases chemotherapy or radiotherapy is added to reduce the risk of recurrence. The earlier the cancer is found, the less invasive the treatment can be. Read more about symptoms and work-up on the page about blood in the stool.

Benefits of taking part

Found earlier: cancers and pre-cancerous changes picked up by screening are more often localised, and the outlook is generally better when disease is found early.

Treatment options: the stage at diagnosis affects which treatments are possible, but the plan also depends on tumour factors and your general health.

Drawbacks and caveats

False alarm: blood in the test may come from harmless causes like fissures or haemorrhoids, but still triggers worry and further work-up.

False reassurance: a negative test is not a guarantee. If you develop symptoms – change in bowel habit, blood or mucus in the stool, abdominal pain, unexplained fatigue or weight loss – contact your GP, even if you have just been screened.

Discomfort: bowel cleansing and colonoscopy can feel uncomfortable. We offer sedation and pain relief as needed.

Overtreatment: some polyps removed at colonoscopy would never have become cancer.

Symptoms you should always act on

• Change in bowel habit lasting more than four weeks.
• Blood or mucus in the stool.
• Unexplained weight loss or fatigue.
• Persistent abdominal pain or a feeling that the bowel does not empty properly.

How the clinic can help

With a GP referral we offer colonoscopy as follow-up to a positive FIT test or for symptoms suggesting bowel disease. For suspected cancer we accept referrals in the fast-track pathway, where the Danish Health Authority standard timeframes apply. See also [blood in the stool, polyp removal and colonoscopy.

Sources

This page is based on the Danish Health Authority's Pakkeforløb for kræft i tyk- og endetarm (2022), sst.dk/da/udgivelser/2022/pakkeforloeb-for-kraeft-i-tyk-og-endetarm, and on Patienthåndbogen at sundhed.dk, Screening for tarmkræft. Both retrieved 15 August 2026.