The Bowel Cancer Screening Programme in England is on course to cut bowel cancer deaths by 16 per cent, according to a University of Nottingham-led study of the first 1 million test results.
But the survey suggests that better screening techniques should be developed because bowel cancers on the right side of the body were not as likely to be picked up as those on the left.
Bowel cancer kills 16,000 people every year in the UK and is second only to lung cancer as the leading cause of cancer death in the UK and Europe. Survival from the disease is still only around 50% and is significantly lower than in other comparable countries.
The findings of the report are based on an examination of the first 1 million faecal occult blood tests from patients who took part in the first round of bowel cancer screening in England. The screening programme for people between the ages of 60 and 69 started in 2006. It involves three tests every two years and has since been extended to those over 70.
The analysis of the screening programme has just been published in the journal ‘Gut’. It shows that a much higher proportion of cancers detected were on the left side of the bowel. As a result, different techniques may now be used to pick up the disease on both sides of the body, as the right-sided disease is believed to be more aggressive.
Richard Logan, from the University’s Division of Epidemiology, who led the study, said: “It’s not yet fully understood why cancers on the right-hand side were not showing up during screening.
It’s possible that they grow faster, and are more likely to be diagnosed conventionally, or that they were less likely to bleed and trigger a positive test result.”
Professor Logan believes that the current blood test should be replaced by a more efficient alternative which might be more sensitive. He said: "There is a much better test available, but it will cost money to introduce it, and that money is not currently there."
By October 2008 around 2 million people had been invited to take part in the screening programme and around half had accepted. In all, 2.5% of men and 1.5% of women (21,106 people in total) had an abnormal test result and 17,518 people were investigated further.
Most underwent colonoscopy – a procedure which uses a small camera to examine the inside of the bowel. Men were more likely to have bowel cancer and its precursor (higher-risk adenomas), than women.
These were found in around one in eight (11.6%) and around four out of 10 (43%) men, respectively, compared with just under 8% and 29%, respectively, of the women.
Seven out of 10 cancers (71%) picked up by the screen were early stage disease, and as expected, right sided cancer was more common in women than in men. But left sided cancers were considerably more common than expected, based on figures drawn from cancer registries.
These figures indicated that around two thirds of bowel cancers (66%) picked up by the screening programme would be left sided and around one in four (24%) would be right sided. Instead, more than three out of four (77%) cancers detected by screening were left sided, compared with 14% that were right sided.
The authors point to research suggesting that right sided cancers are more aggressive and less likely to be picked up by screening. The report concludes that different screening strategies may be required to effectively screen for right-sided bowel cancer.
