Does Aspirin Cut Cancer Risk?

Regular use of aspirin seems to cut the risk of cancers of the throat, mouth and esophagus by two-thirds, according to research published in the British Journal of Cancer.

Don't, however, reach for that aspirin bottle just yet.

With the data available to date, aspirin probably will do you more harm than good, says Paul F. Castellanos, M.D., assistant professor of surgery at the University of Maryland School of Medicine, medical director of the Center for Voice, Swallowing and Esophageal Disorders, and a member of the Greenebaum Cancer Center at the University of Maryland Medical Center.

The risk of significant bleeding, a known problem with regular aspirin use, calls for a careful weighing of risk and benefits, he cautions.

"One of the big problems with studies of this type is that they weren't trying to discern cancer-suppressing properties; (rather) they were noticing this (trend) in a group of patients. This is known more as phenomenology or the study of events not mechanisms or causality," Castellanos says.

The research, done in Italy, combined data from three studies involving 965 cancer patients and 1,779 people who were hospitalized for other health problems. All of them completed questionnaires about smoking and drinking and how often they took aspirin, among many other practices and health issues. Those who had taken aspirin regularly were at one-third of the risk for cancers of the mouth, throat and esophagus - the first such research to show aspirin may reduce the incidence of these cancers.

But conclusions based on the coincidence of a difference in risk for developing a certain category of malignancy and the use of an analgesic like aspirin is not something on which to base a new theory of cancer prevention, Castellanos says.

In their introduction, the Italian researchers acknowledge there are several earlier reports that come in on both sides of the correlation controversy, i.e., some found an association with cancer risk and aspirin use and others did not. This prompted them to look at this question again.

"Fair enough," Castellanos says, "but this should be done in the context of a prospective randomized study with risk-factor matched controls. They state that their cohorts were matched, but they do not give the details of how they did this and thus do not give the reader a chance to decide if it was done well enough."

He continues, "They present hypothetical explanations for how aspirin may be benefiting the patients in the three studies that were blended, but they have no data to back any of the assertions. More importantly, they do not acknowledge any of the work describing the added morbidity and mortality associated with regular aspirin use in the context of heart disease. This risk and benefit analysis has prompted many in medicine to recommend against general aspirin use absent known risk factors for heart disease or a diagnosis of coronary artery occlusion."

What is known, he says, is that chronic inflammation in the mouth is strongly associated with increased cancer risk. Known causes of inflammation are periodontal disease, smoking and drinking alcohol, and uncontrolled gastroesophageal reflux, according to Castellanos.

Taking aspirin might help suppress that inflammation, which would explain what appears to be a preventive effect. But those causes of inflammation can be reduced with proper dental care, quitting smoking and controlling reflux, without the risks associated with aspirin use.

So why not take aspirin to be on the safe side? The risk of aspirin-associated bleeding is simply too great.

"You can't work hard to prevent one thing without potentially causing two or three other problems," Castellanos says, adding the bleeding caused by aspirin is not a meaningless issue.

"I'm a surgeon, and I've operated on people who were taking aspirin and didn't tell me," he says. "Tiny incisions can bleed profusely. I don't recommend people start taking aspirin for cancer prevention - I'll have to see much more data before I think the benefits will outweigh the risks. In short, while interesting and well done, this paper is a purely a report of an interesting coincidence, nothing more, and should not be used to alter care until much more work is done."

Source:

Paul F. Castellanos, M.D., assistant professor of surgery at the University of Maryland School of Medicine, medical director of the Center for Voice, Swallowing and Esophageal Disorders, and a member of the Greenebaum Cancer Center at the University of Maryland Medical Center

This article was reviewed and updated June 2007.