PHILADELPHIA - People at average risk for colon cancer shouldn't take aspirin or painkillers like ibuprofen to try to prevent the disease, a federal task force advises, because of the risk of bleeding and other potential health problems. The recommendation for the first time by the US Preventive Services Task Force includes those with a family history of colorectal cancer.

The panel said that potential risks of taking more than 300 milligrams a day of aspirin or non-steroidal anti-inflammatory drugs, such as ibuprofen and naproxen - brand names include Motrin, Advil and Aleve - include a higher risk for stroke, intestinal bleeding or kidney failure.

Those risks outweigh the potential benefits of preventing cancer, the task force said in Tuesday's issue of the Annals of Internal Medicine. The task force said that while there is good evidence that low doses of aspirin, usually less than 100 milligrams, can reduce the risk of heart disease, it does not lower the rate of colon cancer.

Colorectal cancer is the third most common type of cancer in men and women and is the second-leading cause of cancer-related deaths in the United States, killing about 56,000 people each year. About 150,000 new cases are diagnosed annually.

Most of those diagnosed are over the age of 50, and 20 percent have a parent, sibling, grandparent, aunt or uncle with the disease. Blacks have the highest rate of colorectal cancer of any group.

In 2002, the Preventive Services Task Force recommended that people age 50 and older be screened for colon cancer.

Previous studies had suggested that a daily baby aspirin could prevent precancerous polyps that sometimes become colorectal cancer. But later research showed low-dose aspirin did little good at actually preventing cancer.

Dr. Raymond DuBois, director of the Vanderbilt-Ingram Cancer Center in Tennessee, said he believes the task force's latest advice is reasonable.

"I think for the general population, the risk of either having some gastrointestinal bleeding from aspirin or cardiovascular side effect from some of these other medications ... probably outweighs their use for colon cancer," he said.