Bowel cancer is the third most common cancer worldwide, with over a million new patients being diagnosed each year. In most cases, the cancer develops from tiny, slow-growing nodules on the bowel wall, known as polyps, which can be detected and removed during a ‘colonoscopy’ camera examination. Doctors currently remove all polyps that they see because they cannot tell which ones will turn cancerous.
Like all invasive procedures, having a colonoscopy carries a small risk of complications. Although these complications are rare, cutting off polyps can occasionally cause bleeding or even leave holes in the bowel wall. Because of this, doctors want to find drugs or dietary supplements that can shrink existing nodules and prevent new ones from forming. If effective ‘polyp prevention pills’ could be found, then patients at risk of developing these pre-cancerous bowel nodules would need far fewer ‘check-up’ colonoscopies.
Previous studies have shown that a substance found naturally in fish oil known as Eicosapentaenoic acid (EPA) and aspirin can – each taken on their own – provide some protection against bowel polyps. Taken together, the protective effect may be even greater, as researchers now intend to find out.
“A major advantage of EPA and aspirin is that they are both safe, have few side effects and they are already used widely by people who have heart disease or who have had a stroke,” said Professor Mark Hull from the University of Leeds who is leading the trial. “Other drugs that have been shown to prevent bowel polyps have been linked to an increase in heart attacks, so they are unsuitable for widespread use.”
The researchers plan to recruit around 1000 people from the NHS Bowel Cancer Screening Programme (BCSP) in England who have already had several polyps removed. Around 25 to 30 hospitals will be involved.
Some members of the study group will be given both EPA and aspirin. Others will be given just one of the drugs on its own together with ‘dummy’ capsules or tablets, whilst another group of people will only be given the pretend tablets. None of the people taking part in the study or the medical staff will know who is getting the real drugs.
Follow-up camera tests will be used to check how effective EPA and aspirin are at stopping new polyps from forming. Other tests will be carried out on blood, urine and tissue samples to learn more about how both agents work.
“If this treatment is shown to be safe and effective, then in future it could be given to more patients who have been found to have these pre-cancerous bowel polyps and are at risk of developing others in the future,” Professor Hull said.
“Our studies may also indicate which patients the drugs are likely to work in best – another step towards the current vision of personalised medicine.”
The work is being financed by a research grant awarded by the Efficacy and Mechanism Evaluation (EME) programme, which is funded by the Medical Research Council (MRC) and managed by the National Institute for Health Research (NIHR).
Professor Hull and researchers from the Universities of Leeds, Bradford and Nottingham, and South Tyneside NHS Foundation Trust and Gateshead NHS Foundation Trust, will be working with doctors and nurses from the BCSP. The trial is being managed by the Clinical Trials Unit at the University of Nottingham.
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