A new study in Laboratory Investigation adds to a growing body of research suggesting that aspirin could make you less likely to develop some cancers.

Researchers grew breast cancer cells in a lab while adding different doses of aspirin to the containers and found that cells exposed to aspirin were more likely to die. Interestingly, those that survived the aspirin onslaught were left unable to grow. A second part of the study found that aggressive tumors in mice given low-dose aspirin for 15 days shrank by 47 percent, while a group of mice given prophylactic aspirin before they were exposed to cancerous cells saw far less cancer growth than a control group.

An aspirin a day for 10 years could also cut down on bowel cancer cases by 35 percent and both esophageal and stomach cancers by 30 percent, found a 2014 study in Annals of Oncology; the findings also suggested that the regimen lessened the number of deaths from those cancers by 35 to 50 percent. There was also evidence of lower rates of breast, prostate and lung cancers, but those links weren't quite as strong. But ovarian cancer could be another target, as research in the Journal of the National Cancer Institute in 2014 suggested that women who take aspirin daily may lower their risk of developing ovarian cancer by 20 percent.

Where Does Aspirin Get It's Anti-Cancer Mojo?

Exactly how aspirin works isn't entirely understood, but it may have to do with its ability to lower inflammation in the body. (Inflammation has long been linked to the development of cancer, possibly by helping abnormal or cancerous cells divide and conquer.)

Another intriguing theory: Aspirin may stop your platelets from acting as cancer camouflage. "We know aspirin prevents platelets from sticking to each other, which is why it can be beneficial for treating heart disease," says Jack Cuzick, PhD, lead author of the Annals of Oncology study, head of the Centre for Cancer Prevention and director of the Wolfson Institute for Preventive Medicine at Queen Mary University of London. "But recent discoveries suggest that platelets also stick around cancer cells, chaperoning them around the body and hiding them from the immune system, which makes it easier for cancer to spread."

The Caveat: There are Serious Risks to Consider

Last year, the FDA ruled that unless you've already been diagnosed with heart disease, the benefits for heart health don't outweigh the risks that come from aspirin’s role as a blood thinner, like gastrointestinal bleeding and increased risk of bleeding stroke. "Brain bleeds, in particular, can be catastrophic," says Steve Nissen, MD, chairman of the Robert and Suzanne Tomsich Department of Cardiovascular Medicine at Cleveland Clinic's Sydell and Arnold Miller Family Heart & Vascular Institute, who served on the FDA panel that made the ruling.

But it may be a different story with cancer prevention: In the Annals of Oncology study, researchers suggested that for the average person, the benefits far outweighed the possible side effects, particularly for those who took aspirin daily between the ages of 50 to 65. (Over 65, the risks became more pronounced; under 50, the benefits didn't outweigh the risks). Cuzick believes that these findings merit revisiting the aspirin-for-heart-patients-only thinking. "That was before all the evidence on cancer came out," he says. "It's really tipped the balance in favor of aspirin therapy."

There are exceptions though. Aspirin is particularly dangerous for people who have a clotting disorder, are taking other anticoagulants or are prone to bleeding stomach ulcers.

What to Make of It All

The evidence behind aspirin as a cancer-preventer is promising, but it's still in its early stages. Like any other medication or emerging research, you shouldn't take it without talking to your doctor first, especially if you have one of the conditions that puts you at increased risk of side effects.


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