Colorectal Cancer
Cancer of the colon and rectum is one of the few cancers that screening can catch before a cancer has even developed. It grows over years out of benign growths called polyps, which is why treatment succeeds so often when it is found early.
- 45 age screening is advised to start in people at no added risk
- Polyp the removable growth the cancer develops from
- RAS/BRAF gene tests that determine treatment in advanced disease
What is colorectal cancer?
Cancer of the colon and rectum develops as polyps formed on the inner surface of the large bowel gradually turn malignant. That change usually takes years, and it is the reason screening is so effective in this cancer.
Which part of the large bowel the tumour sits in matters. Right sided colon tumours often show themselves through anaemia and fatigue, while left sided colon and rectal tumours do so through a change in bowel habit and bleeding. In rectal cancer the order of treatment is also planned differently from the colon.
Screening and diagnosis
In this cancer the most effective step is screening carried out before any symptom appears.
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Colonoscopy
Both screening and treatment
Colonoscopy does more than make a diagnosis: polyps that are seen can be removed in the same procedure, preventing a cancer from developing. In people at no added risk it is advised to start at 45 and, if the result is normal, to repeat it at set intervals.
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Stool test
Faecal occult blood
A faecal occult blood test is a screening option for people who decline or cannot access colonoscopy, and it needs to be repeated regularly. When the test is positive, a colonoscopy must follow.
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Staging
Establishing the spread
After diagnosis the liver and lungs are assessed with computed tomography, and in rectal cancer a pelvic MRI is also performed. The stage determines the timing of surgery and the need for additional treatment.
Treatment approaches
In early stage colon cancer the basis of treatment is surgery; in patients with lymph node involvement, chemotherapy after the operation reduces the risk of recurrence. In rectal cancer, radiotherapy and chemotherapy are often given before surgery.
In advanced disease treatment is planned according to the gene profile of the tumour. RAS and BRAF status, together with whether the tumour lies on the right or left side of the bowel, determine which targeted drug is suitable. In MSI-high patients immunotherapy comes to the fore. Where spread is limited to the liver, surgery can still offer a chance of cure.
Inherited links and prevention
A small share of colorectal cancer is inherited; in the large majority, risk factors that can be changed play a part.
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Lynch
Lynch syndrome
It arises from inherited changes in the DNA repair genes (MLH1, MSH2, MSH6, PMS2) and markedly raises the risk of colon and uterine cancer. It should be investigated in patients diagnosed at a young age or with more than one case in the family, since the result affects both the follow-up plan and the patient's relatives.
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Lifestyle
Risks you can change
Processed meat, inactivity, excess weight, smoking and alcohol raise the risk, while a diet rich in fibre and regular physical activity lower it. These do not take the place of screening; they are considered alongside it.
Frequently Asked Questions
I saw blood in my stool. Is it cancer?
Most of the time the cause is a benign condition such as haemorrhoids or an anal fissure. But a polyp or a tumour can also lie behind that bleeding, and the two cannot be told apart by appearance. Blood in the stool is therefore a finding that needs to be assessed whatever your age.
At what age should a colonoscopy be done?
In people with no additional risk factor it is advised to start at 45. Where there is a family history of colon cancer or polyps, that age is brought forward, usually to ten years before the age at which the youngest case in the family was diagnosed. The individual plan should be set with your doctor.
A polyp was removed. Will I get cancer?
Removing the polyp prevents a cancer from developing out of it. New polyps can form, however, so colonoscopy needs to be repeated at set intervals. The interval is decided by the number and size of the polyps and the pathology result.
Does rectal cancer mean a permanent stoma?
Not in every patient. The distance of the tumour from the anus is decisive, and with today's pre-operative treatments bowel continuity can be preserved in many patients. In some, a temporary stoma is formed and later closed. This should be discussed in detail with the surgeon before the operation.
Is cure possible in advanced colon cancer?
If the spread is limited to the liver or lungs and is operable, patients in whom drug treatment and surgery are planned together can have a long disease-free period, and cure is possible. That is why multidisciplinary assessment matters in advanced disease as well.