Professor Patrick Morrison from Belfast's Queen's University and colleagues focused on people with Lynch syndrome, an inherited genetic disorder that causes cancer by affecting genes responsible for detecting and repairing damage in the DNA.
Around 50 percent of those with Lynch syndrome develop cancer, mainly in the bowel and womb, but the researchers looked at all cancers related to the syndrome.
The study, published in The Lancet, found almost 30 percent of the patients not taking aspirin had developed a cancer, compared with around 15 percent of those taking the aspirin.
"This is a huge breakthrough in terms of cancer prevention," Morrison said in a statement. "For anyone considering taking aspirin I would recommend discussing this with your doctor first as aspirin is known to bring with it a risk of stomach complaints, including ulcers."
Morrison said the study involved 43 centers in 16 countries that tracked nearly 1,000 patients for up to 10 years.