Aspirin May Boost Breast Cancer Survival, But Clinical Trials Are Needed

The original maker of aspirin, Bayer AG, probably couldn't be happier: Its so-called wonder drug is already famously touted as helping to lower the risk of heart attacks and strokes, and the list of diseases and disorders that it and other nonsteroidal anti-inflammatory drugs (NSAIDs) combat continues to grow. Now, a new study published in the Journal of Clinical Oncology says we can add another benefit to aspirin's resume: breast cancer survival.The study of 4,164 women who had been diagnosed with breast cancer showed that women taking aspirin regularly are 50% less likely to die and had a 50% lower risk of the cancer returning.

The study was led by Dr. Michelle Holmes of Harvard Medical School; she and her colleagues evaluated aspirin use among women participating in the Nurses' Health Study at least one year after they had been diagnosed with breast cancer.

Interestingly, those who took aspirin most often -- six to seven days a week -- had only a 64% lower risk of death during the follow-up period, compared to a 71% risk reduction among those who took aspirin two to five days a week. Similarly, the risk of the cancer spreading was reduced by 43% and 60%, respectively. The researchers didn't have access to exact doses, however.

"This is the first study to find that aspirin can significantly reduce the risk of cancer spread and death for women who have been treated for early-stage breast cancer, " said Holmes. "If these findings are confirmed in other clinical trials, taking aspirin may become another simple, low-cost and relatively safe tool to help women with breast cancer live longer, healthier lives."

Experts Urge Caution

And therein lies the crux of the problem with celebrating these results immediately: They are based on data from an observational study, which does not establish definitive cause and effect, as opposed to a clinical trial, which does. Essentially, the Nurses' Health Study is a massive, decades-long examination of how an array of lifestyle choices impact the participants' health.

So, while the findings do agree with earlier studies in colon cancer patients, as well as with lab results showing that aspirin inhibited the growth of breast cancer cells, a proper clinical trial still needs to be done. Holmes postulates that it may be the anti-inflammatory properties of aspirin that are at work here, as cancer is being viewed more and more in by medical professionals as an inflammatory disease.

But aspirin (generically, acetylsalicylic acid) can also cause gastrointestinal ulcers and bleeding. It is for these reasons that the medical community revised its "aspirin-a-day" mantra to target only people with certain risk factors for heart attacks and strokes.

Aspirin's Benefits Come With Certain Risks

Another cautionary note: Some previous conclusions based on data from the Nurses' Health Study have turned out to be wrong, most famously, the study which suggested that vitamin E lowered rates of heart disease. The effect could not be reproduced in randomized clinical trials.

It is for these reasons that women who have had breast cancer should not start taking aspirin on a regular basis without consulting their doctors, Holmes says. Eric Jacobs of the American Cancer Society stresses this as well: "It would be premature for breast cancer survivors to use aspirin in order to reduce risk of breast cancer recurrence or of dying from their disease."

Even more important, aspirin should not be considered a substitute for established cancer treatments. And during cancer treatments, aspirin is usually avoided because it can act as a blood thinner, which could further increase complications.

An aspirin a day -- or every other day? Only if your doctor says yes.
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