Blood tests that can identify patients with bowel and stomach cancers have been devised by scientists, raising the prospect of rapid, population-wide screening for the tumours.

Studies by teams in Belgium and Germany have shown that gastrointestinal cancers can be detected and assessed for their risk of spreading through a blood sample rather than the more complex tests now in use.

The studies, to be presented today in Berlin at the annual congresses of the European Cancer Organisation and the European Society for Medical Oncology, could make national detection programmes easier to introduce, more cost-effective and less unpleasant for patients than present methods.

The first study, led by Dr Joost Louwagie, of OncoMethylome Sciences, based in Belgium, involved the use of DNA tests to identify patterns of methylation — a process by which genes are switched off. This is linked to the progression of tumours. Blood samples were taken from 193 patients known to have bowel cancer, as well as 688 controls undergoing colono-scopy for cancer screening, and tested for particular methylated genes that could show differences between normal and cancerous tissues.

The scientists evaluated the best methylated genes — identifying FOXE1 and SYNE1 as the most accurate indicators — with the ultimate goal of providing a specific and patient-friendly option for screening.

Bowel cancer kills more than 16,000 people in the UK annually — almost half of all diagnoses. More than 80 per cent of cases are in the over-60s. Early detection, when a tumour is most treatable, can improve outcomes. There are two effective methods — stool analysis and colonoscopy — but both have drawbacks.

Colonoscopy, where the interior of the colon and rectum is examined using a tiny camera mounted on a flexible tube, is the most sensitive test available and has the benefit of allowing removal of pre-cancerous polyps. However, it is invasive, expensive and requires bowel preparation and skilled practitioners.

A national screening programme involving stool analysis — known as faecal occult blood testing (FOBT) — is being introduced and is due to be completed by the end of this year. FOBT is less invasive and inexpensive, but compliance is often less than 50 per cent because of patients’ reluctance to handle stool samples.

Dr Louwagie said: “Giving a blood sample could become part of the regular physical examination. It will not replace colonoscopy, but provide a way of screening a larger part of the population in a more patient-friendly manner so that more cancers are detected and treated successfully.”

A second study, to be presented today in Berlin, provides further evidence of the possibilities of blood screening. The German research team, from ECRC Charité University of Medicine and the Max-Delbrück-Centre for Molecular Medicine, found a genetic marker associated with the spread of cancer cells in RNA molecules. The scientists said that, as well as helping to diagnose colon, rectal of gastric tumours, the test could predict the likelihood of metastatic disease, when tumours spread, in patients after diagnosis of these cancers.

>>>Both research teams emphasised that prospective studies — where people not known to have cancer are screened — were needed to gather further evidence of its wider application.

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