Should All Adults Take a Daily Aspirin?
Jack Cuzick says it’s clear that aspirin can reduce cancer risk; Lianne Marks warns of dangerous side effects
March 22, 2015 11:00 p.m. ET
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Photo: CorbisThe medical guidelines surrounding aspirin therapy can be confusing.
Most doctors agree that an aspirin a day is a good idea for people who already have had a heart attack or stroke, but opinions differ on who, if anyone, should take aspirin to prevent a problem from happening in the first place, a use known as primary prevention.
The controversy centers on the painkiller’s blood-thinning properties: While studies have shown that aspirin offers protective benefits against cardiovascular disease and certain cancers, they also have shown that aspirin use can cause bleeding in the stomach and brain.
The question is, do the benefits outweigh the risks for generally healthy people?
The Food and Drug Administration doesn’t think so. Some researchers, however, believe the tide will turn in aspirin’s favor once the growing body of cancer evidence is fully evaluated.
Jack Cuzick, director of the Wolfson Institute of Preventive Medicine at Queen Mary University of London, argues in favor of general aspirin use, saying the benefit far outweighs the risks; Lianne Marks, assistant dean for educational development and regional chairwoman for internal medicine at Texas A&M Health Science Center College of Medicine, believes the risks are just too great.
YES: The Evidence Is Clear It Reduces Deaths From Cancer
By Jack Cuzick
If you are a middle-aged adult at low risk for bleeding, there is a simple, low-cost way to reduce your chances of dying from cancer and to a lesser extent heart disease: Take a daily baby aspirin.
A group of international experts reached that conclusion after conducting a formal benefit/harm analysis on aspirin use in the general population. Our study, published in the Annals of Oncology, found that overall for both men and women aged 50 to 65 the benefits of 10 years of low-dose aspirin outweigh the risks of gastrointestinal bleeding and other complications by a large margin.
Specifically, we estimated that daily aspirin could prevent 4% of all deaths in the next 20 years, mostly due to reduced cancer mortality. In terms of cancer prevention, that is exceeded only by avoiding tobacco use and is comparable to reducing obesity but much easier to achieve. Eight deaths from cancer and heart disease would be prevented for every death from gastrointestinal bleeding or stroke. Those are pretty good odds!
Cancer fighter
Many clinical trials have shown a clear reduction in colorectal cancer from aspirin use, and long-term follow-up of those studies suggests aspirin offers protection against other types of cancers, too.
Aspirin seems to have the biggest effect on colorectal, esophageal and stomach cancers, where reductions in excess of 30% were seen both for the development of new cancers and deaths. Smaller but fairly consistent benefits have been reported for lung, prostate and breast cancer, with both incidence and mortality reduced between 10% and 15%. Over 150 observational studies have also confirmed these findings.
Why has it taken so long for aspirin’s anticancer benefits to be discovered? The benefits don’t occur right away, so early follow-up of the clinical trials failed to observe them. It is now clear that at least five years of aspirin use is needed for aspirin’s anticancer properties to kick in, and that the benefits are sustained for many years after aspirin use has stopped. How long this carry-over effect lasts needs to be studied further to determine when to stop aspirin, since the bleeding side effects become more serious after age 70.
Aspirin use isn’t without potential side effects, and those who oppose its routine use may cite studies showing higher-than-acceptable rates of bleeding complications to bolster their case.
We consider such studies to be outliers. We found serious complications to be rare, with one extra major bleeding event requiring hospitalization occurring for every 300 individuals who take aspirin for 10 years. Aspirin also can increase the incidence of hemorrhagic strokes due to bleeding in the brain, but these events are even more rare and are balanced by a similar reduction in the more common occlusive strokes associated with blood clotting. Still, because hemorrhagic strokes are more often fatal, the small number of people with higher bleeding risks (mostly those with diabetes or hypertension, or who take blood thinners) shouldn’t use aspirin without consulting a doctor.
Changing the equation
When aspirin is evaluated solely in the context of cardiovascular disease, its protective effects are less pronounced, which is why major health organizations don’t recommend it for primary prevention. But the growing body of cancer data tips the benefit-risk calculation strongly in aspirin’s favor, and I expect those recommendations to change once that evidence is fully evaluated.
Many things still need to be discovered to refine our use of aspirin for cancer prevention, but that shouldn’t deter people from making use of the clear information we have now.
Dr. Cuzick is director of the Wolfson Institute of Preventive Medicine at Queen Mary University of London. Email him at reports@wsj.com.
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