Screening for bowel cancer
Screening is the systematic application of a test or inquiry, to identify individuals at sufficient risk of a specific disorder to benefit from further investigation or direct preventive action, among persons who have not sought medical attention on account of symptoms of that disorder.
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The current NHS bowel cancer screening programme is geared more towards early detection of cancer rather than detecting and treating a pre-cancerous condition (in this case certain bowel polyps). From age 60, men and women are offered the opportunity to use a screening kit which is posted to them. Small samples of 3 consecutive bowel actions are placed on a special card which is hygienically sealed and sent back Freepost. If sufficient traces of blood products are discovered, faecal occult blood (FOB), which will occur in 20 people out of every 1000, a referral for a colonoscopy is made. 2 of those 20 people will have a bowel cancer. Between 6 and 8 others will have bowel polyps which can be removed as some of these could develop into cancer.
Frequent questions about the process.
Screening works best for cancer when it is able to detect a pre-cancerous condition that can be simply treated in a low risk manner.
Recent UK research has shown that flexible sigmoidscopy< screening between the ages of 55 and 64 can reduce the risk of dying from bowel cancer by 40%. This test takes only a few minutes and does not require any sedatives nor a special diet and strong laxatives prior to the test. It relies on the fact that two thirds of bowel polyps and cancers will be within the reach of a (relatively) short flexible camera. If a cancer or significant polyps are detected, a full colonoscopy is recommended. Flexible sigmoidoscopy screening has a greater preventative potential than FOB testing. We will have to wait and see if the NHS is able to move over to this method of screening despite an early governmental promise by our current Prime Minister.
Screening by colonoscopy is offered in the USA and has an even greater potential to reduce the risk of dying from bowel cancer but has higher inherent risks and is also more expensive to run.
Some independent companies encourage people to attend for full body screening by the use of CT scans. There is no proven benefit from such screening and the radiation dose needs to be taken into account when it is applied to asymptomatic individuals.