'Eureka moment' as scientists discover how aspirin could stop some cancers spreading

Scientists have discovered how aspirin may stop some cancers from spreading, describing it as a "Eureka moment".

The new research builds on existing evidence suggesting aspirin supports a boost in the immune system to help catch deadly cancer cells.

Clinical trials in cancer patients, examining how aspirin could stop the disease coming back, are ongoing - but experts warn against routinely taking aspirin without speaking to a doctor.

The new research suggests a path for aspirin to become a cancer treatment, alongside the development of more effective drugs to prevent cancer spreading.

Researchers screened 810 genes in mice and found 15 that impact the spread of cancer.

Mice lacking a gene which produces a certain protein, called ARHGEF1, were less likely to have cancer spread to the lungs and liver, the study found.

Scientists found that ARHGEF1 suppresses a type of immune cell called a T cell, which is important for recognising and killing metastatic (spreading to other parts of the body) cancer cells.

They unexpectedly discovered the ARHGEF1 is switched on when T cells are exposed to a particular clotting factor, a protein that prevents excessive bleeding.

The clotting factor, called thromboxane A2 (TXA2), is made by platelets in the blood - and aspirin is already known to cut its production.

By decreasing TXA2 production, aspirin can prevent certain cancers from spreading, researchers found.

In mice given aspirin, the frequency of metastases - the spread of cancer - was reduced compared with ones not on the drug, the research, published in the Nature journal and funded by the Medical Research Council and Wellcome Trust, found.

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Dr Jie Yang, from the team which led the study at the University of Cambridge, described the discovery about TXA2 as a "Eureka moment".

"It was an entirely unexpected finding which sent us down quite a different path of inquiry than we had anticipated," Dr Yang said.

"Aspirin, or other drugs that could target this pathway, have the potential to be less expensive than antibody-based therapies, and therefore more accessible globally.

Researchers are now working with Professor Ruth Langley at University College London, who is leading a study into whether aspirin can stop or delay early stage cancers from returning.

Prof Langley said: "This is an important discovery. It will enable us to interpret the results of ongoing clinical trials and work out who is most likely to benefit from aspirin after a cancer diagnosis."

However, she warned: "In a small proportion of people, aspirin can cause serious side-effects, including bleeding or stomach ulcers.

"Therefore, it is important to understand which people with cancer are likely to benefit, and always talk to your doctor before starting aspirin."

(c) Sky News 2025: 'Eureka moment' as scientists discover how aspirin could stop some cancers spreading