Symposium Weighs Use of NSAIDs to Prevent Colon Cancer

August 1, 1997

WASHINGTON--Addressing an American Gastroenterological Association (AGA) symposium on NSAIDs during Digestive Disease Week, Dr. Robert Sandler, of the University of North Carolina, Center for Gastrointestinal Biology and Disease, posed two questions:

WASHINGTON--Addressing an American Gastroenterological Association (AGA)symposium on NSAIDs during Digestive Disease Week, Dr. Robert Sandler,of the University of North Carolina, Center for Gastrointestinal Biologyand Disease, posed two questions:

  • Do these compounds prevent colorectal cancer?
  • Should we use them?

Quoting his favorite social philosopher, former NY Yankee catcher YogiBerra, Dr. Sandler advised, "You can observe a lot by watching."

To answer the first question, Dr. Sandler reviewed a series of case-controlstudies, cohort studies, and clinical trials in which researchers assembledsubjects using or not using NSAIDs regularly and then "watched"what happened.

Results of the case-control studies are remarkably consistent, withall showing that NSAIDs do have a protective effect against colorectalcancer.

Among the cohort studies, all but one show a protective effect. Resultsof the randomized controlled trials, although few, are similar. Dr. Sandlercautioned that no randomized trial has lasted longer than five years, andcolon cancer may take up to 10 years to develop.

Should We Use Them?

While the answer to the first question, appears to be "Yes,"the second question is not answered simply. Dr. Sandler cautioned againstextrapolating from results of studies involving high-risk patients to average-riskindividuals.

Also, there is some evidence of decreased efficacy as length of usein-creases. Results are showing a growing number of persons whose polypsregress but who nevertheless develop colorectal cancer. "We may bepreventing polyps, but not cancer," he said.

Finally, since the drugs are not completely without side effects, therisks involved in taking NSAIDs must be considered. "As gastroenterologists,we often suffer from tunnel vision," he warned. "We tend to lookonly at colorectal cancer, ignoring the fact that when we give a systemicagent, it has an effect on a number of different organs."

He called attention to the Guide to Clinical Preventive Services, publishedby the US Preventive Services Task Force in 1996, which declined to recommendaspirin therapy to prevent myocardial infarction (MI) in asymptomatic patientsbecause the "balance of risks and benefits of these therapies . .. is not resolved."

Death from MI is six times more prevalent than death from colorectalcancer, Dr. Sandler said. "If you can't recommend using aspirin toprevent MI, I don't think you can recommend it routinely to prevent colorectalcancer."

For individuals at average risk for development of colorectal cancer,Dr. Sandler argued that 70% to 90% of cases can be prevented by regularcolonoscopic surveillance. For those with a family history of colon canceror polyps, he recommends endoscopic surveillance. For patients with familialadenomatous polyposis (FAP), surgery is the most effective approach.

He did suggest, however, that aspirin therapy might be appropriate intwo settings. For patients with frequent polyps, the use of aspirin orother NSAIDs could reduce the necessary interval for colon-oscopy and mightalso reduce the size of the polyps. He also recommended the use of NSAIDsin the context of randomized controlled trials designed to learn more aboutdose, duration, and toxicity.

The ideal chemopreventive should be safe, effective, and nontoxic overthe long haul. While aspirin and the nonsteroidals are promising, theyare risky, he said. Until more definitive chemopreventive studies are available,Dr. Sandler recommends steering average-risk patients to a sensible low-fatdiet, regular exercise, and avoidance of obesity. And hold the aspirin.