Bowel cancer could be prevented by screening, according to major new study
A single bowel examination at around age sixty, with on-the-spot treatment for precancerous growths, could dramatically reduce the number of deaths from bowel cancer.
Published in the Lancet, a major new study by Cancer Research UK scientists found that screening looks capable of cutting incidence and mortality from the disease by 40 per cent in the target age range.
The trial, which involved 170,000 people, tested the ability of a technique called flexible sigmoidoscopy to detect and prevent bowel cancer. It found that screening is feasible, safe and effective, with the potential to prevent around 5,000 cases of the disease each year in the UK.
Bowel cancer is the third most common cancer in the UK, affecting 34,000 people annually. It often develops from small growths called polyps, some of which are precancerous adenomas that can eventually progress to full blown cancer. This process takes about 10 years, during which time bowel cancer can be prevented by removing the benign growths.
With flexible sigmoidoscopy, doctors insert a long, thin tube, fitted with a miniature camera, into the lower part of the bowel. This allows the detection of polyps and adenomas. Small growths can be removed on the spot, while patients with larger growths may be given a whole-bowel examination, called a colonoscopy.
Researchers set up the screening trial as the NHS would run a national programme. A total of 57,000 people were invited to screening, with 40,000 of them agreeing to a bowel examination. These are being compared to an unscreened group of 113,000 people.
A quarter of people screened had polyps removed from the lower bowel, half of which were adenomas. Cancer was detected in 3 people per 1000 screened, at least 60 per cent at a very early stage.
Scientists believe that with these detection rates, the removal of the polyps and adenomas is likely to reduce the incidence of bowel cancer by 40 per cent in the target group. Earlier diagnosis in those people who had already started to develop cancer should also improve survival from the disease, since when bowel cancer is detected early it is curable in 90 per cent of cases.
Lead researcher Dr Wendy Atkin, of Cancer Research UK's Colorectal Cancer Unit in London, says: "Using a miniature camera to screen for bowel cancer is relatively simple and easy to administer, and I believe it could work very well as part of a national screening programme.
"Unlike some tests for bowel cancer, our system doesn't just detect cancer at an early stage, it can uncover growths before they've become cancerous. And because it takes so long to go from the polyp stage to full blown cancer, a single bowel examination should offer protection from the disease for up to 10 years afterwards."
Dr Atkin and her colleagues will follow the people who have been screened for several more years, to assess the extent to which the removal of polyps and adenomas has prevented cancer.
She adds: "Screening should almost pay for itself, because we expect its cost would be mostly offset by the savings made by preventing the disease and avoiding the costs of treatment."
Just a small percentage of people found the procedure painful, while the vast majority were glad afterwards that they had agreed to screening.
Prof Jane Wardle, Head of Cancer Research UK's Health Behaviour Unit, monitored the psychological impact of the screening programme. She says: "The great thing about this kind of screening is that it doesn't cause much worry or anxiety. In most cases a positive test will simply mean the detection of harmless, precancerous growths that can be removed on the spot. We saw a very good uptake for the scheme, with 71 per cent of those invited for screening turning up at the clinic."
Sir Paul Nurse, Director General of Cancer Research UK, says: "This pilot study looked at a huge number of people, and found that screening was feasible, easy to administer, cost-effective and above all capable of detecting and removing a very large number of precancerous growths.
"We expect that the removal of these growths will have a major impact on incidence and mortality, and that a national screening programme would be a very significant health initiative."
Note to editors:
April is Bowel Cancer Awareness Month, which aims to highlight the need for better ways of treating and preventing the disease.