A study of Medicare patients with osteoarthritis provides additional evidence that non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin reduce the risk of colorectal cancer.
Earlier investigations of the drugs, impact on tumor development could not rule out the possibility that an observed protective effect was caused by other preventive health care measures. The current study, led by a Massachusetts General Hospital (MGH) physician, appears in the August 2007 Journal of General Internal Medicine.
"This is good news for people who take NSAIDs regularly for osteoarthritis," says Elizabeth Lamont, MD, MS, of the MGH Cancer Center, the study's lead author. "Although patients face risks such as bleeding or kidney damage from this therapy, they probably are at a lower risk of developing colorectal cancer." Because of the risks posed by the dosage used to treat osteoarthritis, she and her co-authors stress that currently available NSAIDs should not be used solely to prevent cancer.
Earlier randomized trials clearly showed that NSAID treatment can prevent the development of precancerous colorectal polyps, but whether or not such therapy also reduces the risk of invasive colorectal cancer has not yet been confirmed. Those trials used relatively low doses of aspirin and showed no significant differences in colorectal cancer rates between the aspirin and placebo groups. While many observational studies have shown a protective effect of NSAIDs against colorectal cancer, interpretation of some of those results may have been clouded by other healthy behaviors of the participants.
"It would be ideal to conduct a randomized clinical trial , in which half the patients receive NSAIDs at doses higher than those used in prior trials and half receive placebos , and follow both groups for many years for evidence of cancer. But such trials are expensive, time consuming, and could present real health risks to participants. Therefore, we took advantage of a natural ,experiment, by comparing data from patients known to regularly take higher amounts of NSAIDs with that from those taking lower doses in order to evaluate any effect on colorectal cancer risk."