People with a genetic condition that puts them at increased risk of colon cancer may lower their chance of developing the disease by taking daily aspirin, a study suggests.
The finding, however, doesn't apply to the general public, since aspirin can have side effects such as gastrointestinal bleeding.
The 861 people in the British study had Lynch syndrome, a rare, inherited disorder that puts them at high risk for cancers including those of the colon. The condition accounts for about 3 to 5 percent of colon cancer cases.
Previous research had suggested that aspirin could help prevent colon cancer in that group.
In the latest study, people were assigned to take 600 milligrams of aspirin daily _ about two regular strength aspirin _ or dummy pills. After more than four years of follow-up, the study didn't find a significant difference in how many people in each group developed their first colon cancer.
But they did see one when they looked at long-term participants who regularly took their pills for at least two years. Among the 258 people on aspirin, there were 10 colon cancer cases. That compares to 23 cases in the 250 people on dummy pills. Rates of side effects like bleeding and ulcers in the stomach were similar in both groups.
"This is good news for a very specific population," said Asad Umar, a cancer prevention expert at the U.S. National Cancer Institute who was not linked to the study. He said the finding could apply to about 15 percent of colon cancer patients who have genetic defects similar to Lynch syndrome.
But Umar warned aspirin should only be recommended for people at high risk for colon cancer.
"We're not ready to say aspirin is useful for the general public," he said. "There are still a lot of toxicity concerns."
The paper was published Friday in the journal Lancet. It was paid for by groups including the European Union, Cancer Research U.K., Bayer Corporation, the original maker of aspirin, and others.
Newcastle University's Dr. John Burn, the study's chief investigator, reported receiving a speaker's fee from Bayer last year.