Taking 600 milligrams of aspirin daily cut the risk of colorectal cancer in people at high risk for the disease, a new study found.
The study -- the first clinical trial of its kind -- followed 861 people with Lynch syndrome, a genetic condition that raises the risk of colorectal cancer. Out of 427 patients who took two aspirins a day, 18 went on to develop colorectal cancer compared to 30 of 434 patients who took placebo pills -- a risk reduction of 44 percent. And for 258 patients who took aspirin for two years or more, the risk dropped 63 percent.
The study adds to growing evidence that the drug famous for relieving headaches may help prevent cancer, too.
"Our results, taken in conjunction with recent research, provide a basis for recommendation of aspirin chemoprevention in Lynch syndrome as standard of care," reported John Burn, professor of clinical genetics at Newcastle University in the U.K., and colleagues, in The Lancet.
Some experts think the study's implications extend beyond Lynch syndrome, which causes as much as 7 percent of colorectal cancers.
"There's no reason to think the cancers that develop in Lynch syndrome are any different genetically or biologically that those in the general population," said Dr. Scott Lippman, oncologist at the MD Anderson Cancer Center in Houston and co-author of a commentary on the study. "This puts it on the radar for people in the general population to discuss with their doctors."
"Clearly, this is even more incentive for people in that group to take aspirin," said Lippman.
But the drug isn't for everyone. People with ulcers, bleeding disorders, kidney or liver problems should avoid it, as should anyone who might be allergic to it.
The study fills an important gap in research on aspirin and colorectal cancer prevention.
"This is one of the things that was always missing from the aspirin story," said Lippman. "It adds a whole new category of support."
Previous studies relied on observations made during research into aspirin and heart disease -- an afterthought that supported an association but could not prove whether aspirin decreased cancer risk.
But the current study has limitations, too: It was done in Lynch syndrome patients; and it used a high dose of the drug that could tip the risk benefit scale.
"That's a tough one," said Lippman, when asked if he would recommend high-dose aspirin to prevent colorectal cancer. "If someone was at a high risk, had a family history and their doctor agreed to follow them closely, then maybe."
Lippman said he'd feel more comfortable recommending a lower dose, which he thinks would be safer. A 2010 study published in the journal Gut found a 13 percent decrease in colorectal cancer risk in people who took 75 milligrams a day -- a dose even lower than a baby aspirin.
"Another study building on this with a lower dose would be helpful," said Lippman. "In the meantime, I think this should be part of the discussion with primary care doctors."