Studies have long shown that people who have had a heart attack or stroke benefit from a daily aspirin.

Scientists back in the 1970s proved that it could significantly reduce the risk of having another event and/or dying from cardiovascular disease [“secondary prevention”].

Based on those findings, researchers began questioning whether aspirin might also protect people with no known cardiovascular disease [primary prevention]. While studying this question, they also discovered that aspirin could protect against some forms of cancer.

How does aspirin work?

The most common form of cardiovascular disease, or atherosclerosis, starts when fatty deposits called “plaques” form on the walls of the arteries throughout the body. A cardiovascular event, such as a heart attack or stroke, happens when one of these plaques ruptures and causes a sudden blood clot to form. The latter is made, among other things, of platelets and inflammatory cells. The clot then blocks off the flow of blood through that artery. As a result, the tissue downstream of the blockage does not get enough blood and oxygen and is damaged or dies. By inhibiting platelets and inflammation, aspirin could prevent the clot in question from forming.

With cancer, it’s not as clear as to why aspirin might help. Researchers suspect it might prompt cancer cells to self-destruct. They also believe aspirin might reduce inflammation, which seems to promote cancer.

Primary prevention of cardiovascular diseases

Large, well-performed studies have found that in people without established cardiovascular disease, aspirin has the following effects:

• It reduces the risk of heart attack

• It has no significant impact on the risk of stroke

• It has no significant impact on the risk of dying from cardiovascular disease

• Aspirin increases the risk of bleeding (most commonly in the stomach).

Primary prevention of cancer

A number of studies suggest that aspirin prevents both the development of colorectal cancer (cancer of the colon and/or rectum) and lowers the risk of dying from it, an effect likely mediated by aspirin’s possible capacity to inhibit cancerous cells spread. There is also evidence, though weaker, that aspirin may protect against other types of cancer.

Side effects of aspirin

Bleeding: the main problem with aspirin is internal bleeding. Most often, it occurs in the stomach and small intestines, and is not usually fatal. Bleeding can also occur at other sites, with bleeding in the brain being the most serious.

Factors that increase one’s risk of bleeding on aspirin include:

• Having a history of peptic ulcers

• Being 65 years or older

• Being on high doses of medications called nonsteroidal anti-inflammatory drugs, such as Aleve or Advil, often used to treat arthritis and other causes of chronic pain

• Using medications called corticosteroids in pill or injected form, but not when applied to the skin

• Taking anticoagulants or blood thinners, such as warfarin, Pradaxa, Eliquis, Savaysa, or Xarelto.

Aspirin sensitivity

A very small minority of people cannot take aspirin because of a hypersensitivity to the drug. This usually manifests as respiratory symptoms, such as nasal irritation or asthma, but can also manifest as hives or swelling.

Dosing

Experts believe that the protective benefits of aspirin for cardiovascular disease occur at doses of 75 to 100 milligrams a day. While these doses seem to offer all the benefit needed for cardiovascular disease, it’s not as clear which dose would be best for cancer prevention, where higher doses might be better.

Who should take aspirin for primary prevention?

The decision to take aspirin or not, for primary prevention, is one each person should make with his/her healthcare provider after learning about the above potential benefits and risks.

Most experts believe that the benefits of daily low-dose aspirin for primary prevention outweigh its risks in people aged 50 and older, who do not have a high risk of bleeding.

They do not believe that people younger than 50 should take aspirin for primary prevention.

• Joe Yammine is a cardiologist at Bermuda Hospitals Board. He trained at the State University of New York, Brown University and Brigham and Women’s Hospital. He holds five American Board certifications. He was in academic practice between 2007 and 2014, when he joined BHB. During his career in the US, he was awarded multiple teaching and patients’ care recognition awards.

The information herein is not intended as medical advice nor as a substitute for professional medical opinion. Always seek the advice of your physician. You should never delay seeking medical advice, disregard medical advice or discontinue treatment because of any information in this article