(CBS/AP) Aspirin cuts the risk for colorectal cancer in people with a genetic condition that predisposes them to the deadly disease, a new study suggests.
What about the general public? The finding doesn't apply to them, since aspirin can cause side effects including gastrointestinal bleeding.
The 861 people in the British study had Lynch syndrome, a rare inherited disorder that puts them at risk for cancer, including colon cancer. The condition accounts for an estimated 3 to 5 percent of colon cancer cases.
Previous research suggested that aspirin could help prevent colon cancer in that group.
In the latest study, people were assigned to take 600 mg of aspirin daily - about two regular-strength aspirin tablets - or dummy pills. After more than four years of follow-up, the study showed no significant difference in how many people in each group developed their first colon cancer.
But study participants who took their pills regularly for at least two years did show a reduced cancer risk. Among the 258 people on aspirin, there were 10 cases of colon cancer. 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 National Cancer Institute cancer prevention expert 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 aspirin should only be recommended for people at high risk for colon cancer, Umar warned.
"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 Bayer, the original maker of aspirin, and others. The study's lead scientists, Newcastle University's Dr. John Burn, reported receiving a speaker's fee from Bayer last year.
The National Cancer Institute has more on colon and rectal cancer.