Cancer Research UK launches an international study to answer the final questions before aspirin could be recommended to reduce cancer risk.

Studies have estimated that widespread use of low-dose aspirin could lead to a 10% drop in the number of people dying from some cancers, but for every 17 lives saved by preventing cancer or heart attacks, there would be 2 deaths caused by strokes, bleeding, or ulcers.

While research has shown that taking aspirin for 10 years would have benefits for most people between the ages of 50 and 70 years, there needs to be a way to identify those who are at a high risk of bleeding to enable it to be used more widely.

To address this, Cancer Research UK’s epidemiology expert Professor Jack Cuzick, based at Queen Mary University London, is leading an international collaboration of experts to find out who is likely to benefit most from the drug and who is at greater risk of bleeding side effects. The researchers will also investigate what the best dose is, how long to take it, and how aspirin works to reduce cancer risk.

While the mechanism that aspirin uses to reduce pain is well known, little is known regarding how aspirin cuts cancer risk. The researchers hope to unravel this, which could lead to a new drug designed to have the same benefits of aspirin but without the side effects.

The researchers, a collaboration of lab researchers, epidemiologists, and clinical trial experts, from institutes, including Harvard, Newcastle University, and University College London, will also explore why aspirin appears to only have a powerful effect on some cancer types. There is strong evidence that aspirin reduces the risk of bowel cancer, some evidence it can cut the risk of stomach and esophageal cancers, and potentially a number of other cancer types.

Professor Jack Cuzick, Cancer Research UK’s epidemiology expert and lead researcher based at Queen Mary, said: “This is a wonderful opportunity to finally answer the questions that stand in the way of aspirin being more widely used to cut cancer risk. By bringing together researchers from the lab right through to epidemiology—who’ve not had the opportunity to work together before, it will help us to understand how aspirin prevents cancer and who will benefit most.”

This trailblazing work is supported by the Cancer Research UK Catalyst Award, which supports population health researchers to come together and tackle research problems over and above what they could do individually, with funding of up to £5 million over 5 years.

Dr. Fiona Reddington, head of population research at Cancer Research UK, said: “Bringing together the world’s leading researchers to tackle some of the biggest challenges in cancer is at the heart of the Cancer Research UK Catalyst Award. This team will have the unprecedented opportunity to understand the major role aspirin can play in preventing cancer.”

Dr. Robert Strausberg, Chair of the Cancer Research UK Catalyst Award Panel and Deputy Scientific Director of the Ludwig Institute for Cancer Research, said: “Population research has a fundamental role to play in understanding cancer in diverse human populations and in enabling new strategies for prevention, detection, and intervention. That is why I am particularly excited about this Cancer Research UK Catalyst Award funding to investigate aspirin’s role in reducing cancer risk. It is a great example of international scientists from diverse disciplines, such as surveillance, early detection, prevention, and clinical research, coming together to facilitate big impact research.”