Regular, long-term use of Aspirin - and other nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen - reduces the risk of developing Colon cancer, an analysis of data from the Nurses’ Health Study shows.

However, the relatively large doses required for a protective effect mean that the benefits must be balanced against the chances of major stomach or intestinal bleeding.

The findings are reported by Dr. Andrew T. Chan, from Harvard Medical School in Boston, and his associates in this week’s Journal of the American Medical Association.

Their analysis covered 82,911 women who provided information about their use of painkillers, beginning in 1980. During follow-up through June of 2000, there were 962 new cases of colorectal cancer.

Dr. Chan and his colleagues found a significant benefit of regular aspirin use (at least two tablets per week) in preventing Colon cancer, but not until after more than a decade of use.

The more aspirin taken, the lower the risk, the team found, with those taking 14 aspirin per week for longer than 10 years having the lowest risk - a 53 percent reduction.

Analysis of outcomes associated with non-aspirin NSAIDs, such as ibuprofen or naproxen, showed similar results, with significant benefit at higher doses over 10 years or longer in reducing the risk of early-stage Colon cancer.

However, regular, long-term use of acetaminophen appeared to have no effect on colorectal cancer risk.

Based on their findings, the authors estimate that “use of aspirin at the highest-dose category compared with no use of aspirin would prevent one to two cases of colorectal cancer” among 1000 people over a period of 10 years. However, there would also be “an excess of eight episodes of major gastrointestinal bleeding.”

They therefore conclude that “future studies will need to thoroughly consider the risk-benefit profile for aspirin/NSAID chemoprevention among various risk groups and compare such a strategy with other potential prevention efforts.”

SOURCE: Journal of the American Medical Association, August 24/31, 2005.