Aspirin may help to combat cancer, say scientists

The anti-inflammatory pain killer suppresses a cancer molecule that allows tumours to evade the body’s immune defences, a study has found.

Laboratory tests show that skin, breast and bowel cancer cells often generate large amounts of the molecule, prostaglandin E2 (PGE2).

Aspirin and other members of the “Cox inhibitor” drug family block PGE2 production so that tumours have nowhere to hide.

In mice, combining immunotherapy with aspirin or other Cox inhibitors substantially slowed the growth of bowel and malignant skin cancer.

Professor Caetano Reis e Sousa, who led the team from the Francis Crick Institute in London, said it may make a huge difference to patients.

He said: “We’ve added to the growing evidence that some cancers produce PGE2 as a way of escaping the immune system.

“If you can take away cancer cells’ ability to make PGE2 you effectively lift this protective barrier and unleash the full power of the immune system.

“Giving patients COX inhibitors like aspirin at the same time as immunotherapy could potentially make a huge difference to the benefit they get from treatment.

“It’s still early work but this could help make cancer immunotherapy even more effective, delivering life-changing results for patients.”

The ability of cancers to manufacture PGE2 may be one reason why some experimental immunotherapy treatments have not lived up to expectations.

Professor Peter Johnson, chief clinician at Cancer Research UK, which funded the study published in the journal Cell, said: “PGE2 acts on many different cells in our body, and this study suggests that one of these actions is to tell our immune system to ignore cancer cells.

“Once you stop the cancer cells from producing it, the immune system switches back to ‘kill mode’ and attacks the tumour.

“This research was carried out in mice so there is still some way to go before we will see patients being given Cox inhibitors as part of their treatment.

“But it’s an exciting finding that could offer a simple way to dramatically improve the response to treatment in a range of cancers.”

Caetano Reis e Sousa is a fellow of The Academy of Medical Sciences (elected 2006), a member of the European Molecular Biology Organisation and was made an Officer of the Order of Sant’Iago da Espada by the government of Portugal, his home country, in 2009.

The Francis Crick Institute is an institute dedicated to understanding the scientific mechanisms of living things. Its work is helping to understand why disease develops and to find new ways to treat, diagnose and prevent illnesses such as cancer, heart disease and stroke.