A mass-screening programme for 50- to 70-year-olds could cut the risk of stomach bleeds due to daily doses of aspirin, cancer experts have said. About a third of this group carry the bacteriumHelicobacter pylori, which makes stomach bleeds three times more likely - and antibiotics eradicate it.
Research has shown taking low-doses of aspirin can cut the risk of cancer.
Professor Jack Cuzick said screening would make the choice to take it a "no-brainer".
University of London epidemiology Prof Cuzick told the BBC's Newsnight programme: "The test is cheap and very easy to do, and eradication takes only five days.
"Bleeding is the only major setback.
"It's trying to identify those who are infected that matters."
The society working with an international team of experts on cancer prevention is expected to publish a statement on the risks and benefits of long-term aspirin use within weeks.
"We will say this looks very important and needs to be further evaluated", Prof Cuzick said.
The society first looked into aspirin as a cancer-prevention measure in 2009, and has reconvened as evidence of potential benefits has grown.
Taking low-dose aspirin for five years halves the risk of developing colon cancer, according to data published two years ago by Peter Rothwell, from Oxford University.
But Prof Cuzick told Newsnight the most up-to-date data showed "much stronger results".
Last year, research indicated daily low-dose aspirin cut the risk of dying by 66% for oesophageal cancer and 25% for lung cancer. When researchers looked at all solid cancers together, the risk also fell, by 25%.
This year, the team looked at aspirin's effect on the spread of cancer, and found it reduced the risk of secondary spread to the lungs, liver and the brain by "about half".
Low-dose aspirin is already recommended to cut the risk of heart attack and stroke, but there are no national guidelines on who should consider taking it to prevent cancer, or how much to take.
You can see more on The Aspirin Debate - with Newsnight's science editor, Susan Watts, on BBC Two at 22:30 BST on Monday.