Painkillers such as ibuprofen may interact with a cancer protein to stem tumour growth, research suggests.
The finding could point to new ways of combating prostate and other cancers, scientists have said.
Ibuprofen belongs to a particular class of non-steroidal anti-inflammatory drugs (NSAIDs) known as 'profens'. Another common example is naproxen.
A new study has shown that all profens are processed in the body in the same way, though a protein called AMACR.
AMACR also plays an important role in many types of cancer. It is overactive in almost all prostate cancers and some bowel cancers, as well as several others, and is thought to boost the energy supply to tumours.
The link may explain laboratory evidence that ibuprofen can act against prostate cancer cells.
Dr Matthew Lloyd, who led the University of Bath team, said: "Our study is the first to test other drugs in the same family as ibuprofen systematically and show that they're all processed by the same protein in the body.
"Some early laboratory studies have suggested that high doses of ibuprofen can halt the growth of prostate cancer cells, but the reasons for this aren't well understood."
The study is published in the journal Chemical Communications.