Detecting bowel cancer... with a droplet of blood: How a pioneering new test could revolutionise bowel cancer screening and diagnosis

• Simple blood test could replace an invasive colonoscopy for detecting cancer
• Risks from a colonoscopy include heavy bleeding or perforation of the bowel 
• Test can also detect pre-cancerous conditions like polyps with more accuracy 
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Patients with suspected bowel cancer could soon be diagnosed by the use of a simple blood test rather than an invasive procedure.

The test, which is now the focus of a pioneering British trial, can also detect pre-cancerous conditions such as polyps with much more accuracy.

Experts say the technique – which uses a finger-prick drop of blood collected on a piece of paper – could revolutionise bowel-cancer screening and diagnosis.

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Experts say the technique – which uses a finger-prick drop of blood collected on a piece of paper – could revolutionise bowel-cancer screening and diagnosis

Not only could it pick up the disease much sooner and so increase the chance of survival, it could potentially spare many patients an invasive colonoscopy – a £440 procedure where the bowel is examined using a flexible tube. 

Risks from a colonoscopy include heavy bleeding or perforation of the bowel.

About 41,000 Britons are diagnosed with bowel cancer – a type of colorectal cancer – each year, making it the UK’s second-biggest cancer killer.

Some ten per cent of cases are detected through the national screening programme, according to Cancer Research UK.

The charity asks those aged 60 to 74 to collect a stool sample. But many people are reluctant to do so, and half of kits posted to people are never used.

As a result, many patients are detected only after they suffer blood in their stools, weight loss, tiredness, anaemia, or when they attend A&E as an emergency case due to a bowel blockage caused by a tumour.

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The new test looks for certain molecules in the blood, known as biomarkers, that are released by cancer cells

The new test looks for certain molecules in the blood, known as biomarkers, that are released by cancer cells. In addition, tumours may produce chemicals that change the way the body uses or absorbs certain nutrients from food in the gut.

As a result, the body’s use of protein, carbohydrates and fat may be affected – and this can be detected in the blood.

The test, created by the biomedicine company Universal Diagnostics, measures 30 to 40 markers that are most likely to signify bowel cancer. Results are returned within 24 hours.

Earlier studies show its accuracy is comparable to the stool test, detecting 87 per cent of colorectal cancers.

It also picks up 83 per cent of polyps which can grow into cancer and need removing, compared to a detection rate of just 42 per cent using the stool test.

This means doctors could detect potential cancers at a much earlier stage, removing polyps and preventing cancer before it starts.

The trial at Imperial College Healthcare NHS Trust will collect 660 blood samples from patients referred by their GP for a colonoscopy after a positive result from a screening test.

All will be offered a colonoscopy as well as the blood test. However, if the test can be shown to be accurate, one day patients with a very low probability of colorectal cancer could be offered monitoring instead.

Following the trial, the new blood test could be used in widespread screening programmes.

‘Catching colorectal cancer early is vital to provide a greater chance of survival,’ says Dr James Kinross, consultant colorectal surgeon at Imperial College Healthcare NHS Trust, who is leading the trial. ‘There is a great need for a simple-to-use, non-invasive and accurate test.’

Bowel Cancer UK medical adviser Professor Willie Hamilton adds: ‘Currently just over half of those offered screening by a faecal test take up the offer. A finger-prick test would be more welcome.’