Important advance in bowel screening

A new test for bowel cancer can detect the disease in its early stages and has the potential to save lives through earlier diagnosis, a leading cancer scientist will tell conference delegates.

Speaking at Cancer Research UK’s first annual scientific meeting¹, Professor Ron Laskey will explain that the test is rapid, reliable and could form part of a national screening programme.

The technique – developed by Cancer Research UK and the Medical Research Council – identifies signs of cancer in the faeces. It could be used in conjunction with internal bowel examinations, which Cancer Research UK scientists have shown can prevent many cases of the disease.

Cells are routinely shed from the lining of the bowel into the faeces and scientists realised that testing these for signs of abnormality might be an early way of telling whether cancer was developing.

Prof Laskey, Honorary Director of the MRC Cancer Cell Unit and funded by Cancer Research UK, says: “If detected early, bowel cancer is treatable in the great majority of cases but unfortunately by the time the disease is diagnosed it has often begun to spread around the body. Earlier diagnosis is therefore absolutely key to treating the disease more effectively.

“One approach to diagnosing bowel cancer is to look at the bowel lining directly, but another is to use the faeces – which is after all a ready made sample of bowel cells.”

Prof Laskey and his colleagues tested cells for the presence of a molecule called MCM2, which is involved in making new DNA and is only present in cells that are actively dividing. Normal bowel cells do not contain MCM2, but cancerous or precancerous cells – which have often begun to divide out of control – typically have large amounts of the molecule.

Researchers tested the faeces of two groups of people – bowel cancer patients and healthy volunteers. In the patient group, 37 out of 40 tested positive for MCM2, whereas the molecule was not detected in any of the healthy individuals.

Prof Laskey says: “We’re really excited by our results so far, which suggest that our test is not only sensitive but also specific, in that it does not accidentally pick out healthy people as having bowel cancer.

“Testing for the MCM2 molecule looks an exceptionally promising way of improving diagnosis, not only for bowel cancer but for other forms of the disease too. However, we still need to do larger-scale studies on the new test, and in particular we need to examine it’s effectiveness in people with very early, presymptomatic bowel cancer.”

Cancer Research UK regards the introduction of a screening programme as a critical step in reducing mortality from bowel cancer – the second biggest killer cancer in Britain.

Earlier this year, the charity’s scientists announced results from a large-scale patient trial of a type of bowel examination called flexible sigmoidoscopy, which involves inserting a tube into the bowel fitted with a miniature camera. They assessed the effectiveness of a one-off examination at age 60 followed by treatment for precancerous growths and showed that the procedure could reduce the incidence of bowel cancer by 40 per cent in the target age range.

The charity believes the new faecal test might work well alongside sigmoidoscopy.

Prof Robert Souhami, Cancer Research UK’s Director of Clinical Research, comments: “Testing faeces could be a quick and relatively easy way of screening for bowel cancer, and could work well in combination with bowel examinations, which we’ve already shown can be effective at preventing the disease.

“Neither faecal tests or internal examinations are going to pick up every case of cancer, but the two methods together could prove highly effective in reducing mortality. We still need further and larger studies though, to properly evaluate the effectiveness of this new test.”

Prof Sir George Radda, Chief Executive of the Medical Research Council, says: “These results are very exciting and hold real promise for earlier diagnosis of bowel cancers. The aim of the MRC Cancer Cell Unit is to build on new discoveries in basic cancer research and focus on their potential to provide new treatments and methods of diagnosing and preventing cancer. This work is a major step forward in tackling this common disease.”

ENDS