The Benefits and Risks of Aspirin
Is aspirin the new wonder drug? It’s been around for centuries to treat aches and fever, but recent research suggests that aspirin may have potent powers beyond curing a headache or hangover.
Since 600 B.C., healers have used willow tree bark, which contains an aspirin-like substance, to treat common ailments. In the 1890s, Bayer patented the first production of aspirin, whose chemical name is acetylsalicylic acid. Aspirin quickly became popular to reduce pain.
Through the 1900s, doctors saw that people who took aspirin gained other advantages besides pain relief. In the 1940s, a doctor in California began to prescribe aspirin as a blood-thinner for his heart attack patients.
Since then, scientists discovered that acetylsalicylic acid has several potential benefits. It inactivates platelets, which are involved with blood clotting. It also blocks an enzyme called cyclooxygenase (COX), which helps make chemicals called prostaglandins that are involved in pain, inflammation, and possibly in regulating cell development. Also, people with asthma, other bronchospastic lung disorders, and allergies need to talk to their doctors before taking aspirin.
Aspirin and Heart Disease
Since that Californian doctor began handing out aspirin to his patients in the 1940s, dozens of clinical studies have confirmed that people with heart disease who take aspirin have a lower risk of dying. The American Heart Association currently recommends a daily aspirin to all individuals who have had a heart attack unless they have a special reason they cannot take it. Aspirin may also be useful in preventing stroke in some individuals.
Unfortunately, while aspirin can prevent heart disease , there are people who should not take it. “Although it is in everyone’s medicine closet, aspirin is a real drug,” says John Baron, MD, Dartmouth Medical Center. Aspirin does have side effects, he notes. Aspirin can cause serious injury to the stomach lining resulting in internal bleeding. It also increases the risk of the type of stroke caused by bleeding in the brain. People who have a history of internal bleeding or gastrointestinal problems must be careful about taking this medicine.
Aspirin and Cancer
Currently, researchers are studying possible links between aspirin and cancer. Scientists believe the COX enzyme is involved in cancer development. Blocking this enzyme with aspirin might prevent certain cancers.
The most conclusive evidence comes from research in colon cancer . Researchers had noticed that people who took regular aspirin or other similar COX-blocking drugs did not get colon cancer as often as people who didn’t take these drugs.
Scientists decided to test this observation and in March 2003, two studies found encouraging results. In one study, Robert Sandler, MD from the University of North Carolina, Chapel Hill and colleagues looked for colon polyps, a colon cancer precursor, in 517 people randomly assigned to take aspirin or placebo. They found polyps grew in 70 participants (27%) in the group who took the placebo and only in 43 participants (17%) in the group that took aspirin.
A similar study conducted by Dr. Baron and colleagues found that aspirin modestly reduced the chance of developing new polyps even in individuals with no history of colon cancer. In Dr. Baron’s randomized controlled trial, new polyps were detected in 171 participants (47%) in the placebo group, in 140 participants (38%) in the group who took low dose aspirin (81mg), and in 160 participants (45%) in the group who took high dose aspirin (325mg). The researchers were not sure why different doses of aspirin produced different effects.
These two studies provide strong evidence that taking regular aspirin may lower your chance of colon cancer. But, doctors still aren’t sure whether to promote daily aspirin for the prevention of colon cancer. Dr. Baron notes that to prevent colon cancer you may need to take aspirin or a similar COX-blocking drug for fifteen years or more. “And that’s a long time for people to be at risk for bleeding side effects,” he says.
Studying New Links
Research is underway looking at aspirin’s effect on other cancers, including esophageal , prostate , and breast cancer . In fact, in May 2004, Alfred Neugut, MD and colleagues at Columbia University, New York, observed a beneficial link between aspirin and breast cancer. The researchers asked over 2000 women about whether they ever had breast cancer and if they had used regular aspirin, acetaminophen (Tylenol®), or ibuprofen (Advil® or Motrin®) before getting breast cancer. The results showed that 24.3% of women without breast cancer used aspirin, compared with 20.9% with breast cancer. The researchers theorized that women who used aspirin were less likely to also have breast cancer. While this research is promising, more scientific studies that actually compare aspirin to a placebo need to be conducted before definitive conclusions can be made about its effects in breast cancer.
It appears that aspirin, a common and inexpensive drug, may have many positive effects against cancer and heart disease, two of the most common killers of Americans. But, it is not a wonder drug. “We can’t replace other preventive measures,” says Dr. Baron, “even if aspirin is proven to be effective.” Exercise, healthy diets, and regular health screening still play the major roles in preventing these diseases.
American Heart Association
Food and Drug Administration
Aspirin history. Bayer website. Available at: www.bayeraspirin.com/press/factsheets/aspirin_history.pdf. Accessed July 2, 2004.
Baron JA, Cole BF, Sandler RS, et al. A randomized trial of aspirin to prevent colorectal adenomas. New England Journal of Medicine . 2003;348:891-899.
Mehta P. Aspirin in the prophylaxis of coronary artery disease. Curr Opin Cardiol . 2002;17:552-558.
Sandler RS, Halabi S, Baron JA, et al. A randomized trial of aspirin to prevent colorectal adenomas in patients with previous colorectal cancer. New England Journal of Medicine . 2003;348:883-890.
Terry MB, Gammon MD, Zhang FF, et al. Association of frequency and duration of aspirin use and hormone receptor status with breast cancer risk. Journal of the American Medical Association . 2004;291:2433-2440.
Last reviewed May 2006 by Jill Landis, MD
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