By Will Dunham

WASHINGTON, Feb 10 (Reuters) - Taking aspirin daily may cut one's chances of developing the polyps that can lead to colorectal cancer, giving people at high risk for the disease a useful preventive tool, researchers said on Tuesday.

Colon and rectal cancer kills about 630,000 people a year worldwide, and researchers are eager to find ways for people to lower their risk -- particularly those with a history of precancerous polyps, also called adenomas.

Bernard Cole of the University of Vermont and colleagues combined data from four studies involving 2,698 people from the United States, Canada, Britain, Denmark and France to see if daily aspirin prevented recurrence of these polyps.

The people who took aspirin were 28 percent less likely to develop advanced adenomas than those taking a placebo and 17 percent less likely to develop any adenoma.

"If we can find a way to prevent those precancerous lesions, then we have a really good chance of preventing colon cancer," Cole, whose findings appear in the Journal of the National Cancer Institute, said in a telephone interview.

The people in the four studies all had a history of adenomas or colorectal cancer, and they were followed on average for about three years.

Colorectal cancer is the fourth most common cancer in men and the third in women worldwide, with 1.2 million people getting it annually, the American Cancer Society said.

Colon polyps are growths that commonly develop on the inside of the large intestine. Most are small and do not cause problems, but an adenoma, particularly a larger one, has the potential to turn cancerous. When spotted early, adenomas often can be removed before becoming cancerous.

The findings reinforce the notion raised in previous research that aspirin may help curb colorectal cancer.

"The take-home message here is that when you are getting a colonoscopy, if an adenoma is found, you might want to discuss with your doctor whether aspirin use is something that you might want to do in order to prevent future adenomas," Cole said.

A colonoscopy is a procedure to look inside the colon to detect abnormal growths.

Cole noted that regular use of aspirin also can have serious side effects such as increasing the risk of bleeding. (Editing by Julie Steenhuysen; Editing by Eric Walsh)

AlertNet news is provided by