03.22.12

Can Taking Aspirin Once a Day Reduce Risk of Cancer, Stroke, and More?

Studies out this week found that taking the over-the-counter pill once a day reduces the risk of death from cancer. Anneli Rufus on the wonder drug’s effect on heart disease, asthma, and other afflictions.

According to studies published this week in The Lancet, aspirin radically reduces the risk of cancer. These studies confirm prodigious past research linking aspirin use to reduced rates of heart disease, stroke, Parkinson’s Disease, asthma, and yet more cancers. Can a cheap over-the-counter pill a day make the difference between life and death? Here are 15 statistics on aspirin’s effect on health–both the good and the bad.

1. Taking low doses of aspirin for five years reduces the risk of death from cancer by 37 percent.

The brand-new study that yielded this statistic is one of three published in The Lancet on March 21 and produced by an Oxford University-based team. These studies found that regular low-dose aspirin consumption reduced the risks of cancers of the colon, esophagus, and breast, among other body parts. “I am not at all surprised by these findings, which build on the body of research that I covered in my book,” says cardiologist Keith Souter, author of An Aspirin a Day: the Wonder Drug That Could Save YOUR Life. The Oxford team’s new studies “have been meticulously performed using a large population and they are highly significant,” Souter says.

Peter M. Rothwell, et al. “Short-term effects of daily aspirin on cancer incidence, mortality, and non-vascular death: analysis of the time course of risks and benefits in 51 randomised controlled trials.” The Lancet, doi:10.1016/S0140-6736(11)61720-0.

2. People who take aspirin on at least one day per month are 35 percent less at risk of developing heart disease than people who do not take aspirin on at least one day per month.

“Aspirin is what is known as an antiplatelet drug,” says cardiologist Sarah Samaan, author of Best Practices for a Healthy Heart: How to Stop Heart Disease Before or After It Starts. “That means it inactivates our blood platelets, reducing the likelihood of blood clots...Most heart attacks and strokes are caused by unstable cholesterol plaques which rupture or fissure. The body sees this as an injury and sends blood platelets to the injured site. The platelets contribute to clot formation, which is what ultimately closes off the artery, preventing blood and oxygen from reaching the heart muscle or the brain.” A 2011 Mayo Clinic-affiliated study yielded this statistic.

Xianglin Tan, et al. “Aspirin, nonsteroidal anti-inflammatory drugs, acetaminophen, and pancreatic cancer risk: a clinic-based case-control study.” Cancer Prevention Research, 4(11):1835-41.

3. Regular aspirin consumption reduces the risk of asthma by 22 percent.

“Aspirin reduced the risk of newly diagnosed adult-onset asthma in a large, randomized clinical trial of apparently healthy, aspirin-tolerant men,” write the authors of the Harvard University-based study that yielded this statistic. “This result requires replication in randomized trials designed a priori to test this hypothesis; it does not imply that aspirin improves symptoms in patients with asthma.” Still, aspirin can have the reverse effect, causing asthma attacks in some people, Souter warns.

R. Graham Barr, et al. “Aspirin and Decreased Adult-Onset Asthma.” American Journal of Respiratory and Critical Care Medicine, 175 (2), 120-125.

4. People who take aspirin on at least one day per month have a 26 percent lower risk of developing pancreatic cancer than people who do not take aspirin on at least one day per month.

“Aspirin and other nonsteroidal anti-inflammatory drugs (NSAID) show indisputable promise as cancer chemoprevention agent,” begins the text of the 2011 Mayo Clinic-affiliated study that yielded this statistic. Getting down to specifics, the news is even better: “The association between aspirin use and pancreatic cancer was not significantly affected by pancreatic cancer stage, smoking status, or body mass index. Our data suggest that aspirin use...is associated with lowered risk of developing pancreatic cancer.” According to this study, NSAID use is not.

Xianglin Tan, et al. “Aspirin, nonsteroidal anti-inflammatory drugs, acetaminophen, and pancreatic cancer risk: a clinic-based case-control study.” Cancer Prevention Research, 4(11):1835-41.

5. People who take adult-strength aspirin regularly for at least five years are 30 percent less at risk of developing colorectal cancer than people who do not take aspirin regularly.

According to the American Cancer Society-affiliated study that yielded this stat, aspirin might be great for the gut. But before it performs its cancer-preventative wonders, what harm might it wield? Aspirin’s ugly side effects include indigestion, stomach ulceration, and gastrointestinal bleeding, Souter says: “Aspirin is a potentially very valuable and powerful drug, but it is not suitable for everyone. I do not think that anyone should just start taking it. They should discuss this with their own doctor.”

Eric J. Jacobs, et al. “A Large Cohort Study of Long-Term Daily Use of Adult-Strength Aspirin and Cancer Incidence.” Journal of the National Cancer Institute, 99 (8): 608-615.

6. People who take aspirin regularly for a year or more are about five times as likely to develop Crohn’s disease as people who have not taken aspirin regularly for a year.

The large-scale University of East Anglia-based study that yielded this statistic followed more 200,000 volunteers in five European countries for four years.

Andrew Hart, et al. Research presented at the 2010 Digestive Disease Week conference in New Orleans, La.

7. People who take low doses of aspirin regularly and who already have cancer reduce the risk of metastasis—that is, the spread of that cancer to other body parts—by 55 percent.

One of the most promising aspects of the new Lancet studies, Souter says, is that they show the benefits of very low aspirin doses: a mere 75 mg per day. “The benefit of cancer reduction now seems even greater than the benefit in heart attack and stroke reduction,” Souter marvels, “so the overall benefits may outweigh the risks of taking aspirin.” These risks include gut problems, aspirin-induced asthma attacks, and an increased risk of hemorraghic stroke.

Peter M. Rothwell, et al. “Effect of daily aspirin on risk of cancer metastasis: a study of incident cancers during randomised controlled trials.” The Lancet, doi:10.1016/S0140-6736(12)60209-8.

8. Women who take at least two aspirin per week for at least one month are 40 percent less likely to develop Parkinson’s disease than are women who do not take aspirin regularly.

The UCLA-affiliated study that yielded this statistic found that anti-Parkinson’s effects in aspirin-taking women, but not in aspirin-taking men. Aspirin’s anti-inflammatory powers are afoot yet again: “Markers of neuroinflammation, including activated microglia and increased levels of circulating proinflammatory cytokines, have been observed in the brains and cerebrospinal fluid of patients with Parkinson disease,” write the study’s authors.

Angelika Wahner, et al. “Nonsteroidal anti-inflammatory drugs may protect against Parkinson disease.” Neurology: 60:1043-1044.

9. People who take aspirin regularly for five years or longer reduce their risk of developing cancer in the proximal colon—that is, the upper portion of the colon, including the cecum, appendix, ascending colon, hepatic flexure, transverse colon and splenic flexure—by about 70 percent.

“Aspirin taken for several years at doses of at least 75 mg daily reduced long-term incidence and mortality due to colorectal cancer,” write the authors of the Oxford University-affiliated study that yielded this statistic. The benefit “was greatest for cancers of the proximal colon, which are not otherwise prevented effectively by screening with sigmoidoscopy or colonoscopy.”

Peter M. Rothwell, et al. “Long-term effect of aspirin on colorectal cancer incidence and mortality: 20-year follow-up of five randomised trials.” The Lancet, 376 (9754): 1741-1750.

10. People who have had strokes and are aspirin-resistant—a condition affecting from 5 to 45 percent of the general population—are 10 times more likely to have future strokes as are stroke survivors who are not aspirin-resistant.

Aspirin fails to reduce platelet production in aspirant-resistant individuals. Luckily, aspirin works on most of us. “Aspirin is generally considered standard emergency room treatment when a patient comes in with a heart attack or stroke,” Samaan says. “Aspirin given early on in the course of a stroke can reduce the likelihood of a second stroke, and consequently reduces the risk of dying of the stroke.” Then again: “Since some strokes are actually caused by bleeding in the brain, aspirin can actually make these less common types of stroke worse.”

Peter J. Mason, et al. “Aspirin Resistance and Atherothrombotic Disease.” Journal of the American College of Cardiology, 46(6):986-93.

11. Regular aspirin use reduces the risk of non-fatal heart attack by about one-fifth.

“In people at high risk for heart attack and stroke, aspirin can reduce that risk,” Samaan says of the Oxford University-based study that yielded this stat. “For those who have had coronary stents placed, aspirin is usually mandatory in order to prevent the stent from clogging up. However, aspirin also increases the risk for bleeding...It also slightly but measurably increases the risk for bleeding into the brain. If your risk for heart disease is low, then the potential risks outweigh the potential benefits. That’s why we don’t generally recommend aspirin for people under 50 or for those with no risk factors.”

C. Baigent, et al. “Aspirin in the primary and secondary prevention of vascular disease: collaborative meta-analysis of individual participant data from randomised trials.” The Lancet, 373 (9678):1849-60.

12. Men who take adult-strength aspirin for at least five years regularly are 20 percent less at risk of developing prostate cancer than men who do not take aspirin regularly.

The American Cancer Society-affiliated study that yielded this statistic was large in scale, examining the incidence of 10 types of cancer in more than 146,000 men and women. Nonetheless, the study’s authors warn: “The potential effect of long-term daily use of higher doses of aspirin on cancer incidence remains uncertain.”

Eric J. Jacobs, et al. “A Large Cohort Study of Long-Term Daily Use of Adult-Strength Aspirin and Cancer Incidence.” Journal of the National Cancer Institute, 99 (8): 608-615.

13. Aspirin inhibits ovarian-tumor cell growth by as much as 68 percent.

The University of South Florida-affiliated study that yielded this statistic was not performed on human subjects but on cancer cells in vitro. The results are promising, considering that ovarian cancer kills more than 16,000 women in the United States every year and that the disease’s death rates are rising steadily. “The recent news that aspirin may prevent certain forms of cancer is likely to prompt some people to start taking it,” Samaan says. “But again, we have to look at potential risks versus benefits.”

Hector Arango, et al. “Aspirin Effects on Endometrial Cancer Cell Growth.” Obstetrics & Gynecology, 97 (3), 423-427.

14. Regular aspirin use reduces the risk of colon polyps by 19 percent.

Known as polyps or adenomas, benign tumors in the colon have the potential to become cancerous. In the Dartmouth University-affiliated study that yielded this statistic, more than 1,000 patients recently diagnosed with colon polyps were randomly given either placebos or low doses of aspirin (81 mg). Follow-up colonoscopies three years hence determined the presence or absence of polyps. “Low-dose aspirin has a moderate chemopreventive effect on adenomas in the large bowel,” the study’s authors conclude.

John Baron, et al. “A Randomized Trial of Aspirin to Prevent Colorectal Adenomas.” The New England Journal of Medicine, 348 (19):1939.

15. Women who have taken aspirin regularly for more than years have a 58 percent higher risk of developing pancreatic cancer than are women who never regularly took more than two aspirins per week.

Not all aspirin news is good news. “Extended periods of regular aspirin use appear to be associated with a statistically significantly increased risk of pancreatic cancer among women,” write the authors of the Harvard-affiliated study that yielded this statistic. “In vitro experiments and limited animal studies suggest that aspirin and nonsteroidal anti-inflammatory drugs may inhibit pancreatic carcinogenesis”—but “few studies have examined the association between aspirin use and pancreatic cancer in humans, and the results have been inconsistent.” So don’t invest your life savings in busloads of Bayer.

E.S. Schernhammer, et al. “A prospective study of aspirin use and the risk of pancreatic cancer in women.” Journal of the National Cancer Institute, 96 (1):22-8.