Can aspirin reduce the risk of dying of prostate cancer?

Aspirin reduced the risk of dying by almost 40% in men with prostate cancer, according to a large cohort study presented at the American Society of Clinical Oncology Genitourinary Cancers Symposium (GuCS) in San Francisco. The long-running longitudinal Physicians’ Health Study at Brigham and Women’s Hospital in Boston and the Harvard T.H. Chan School of Public Health has monitored 22,071 men in a span of 27 years, 3,193 of which were diagnosed with prostate cancer – including a subgroup of 403 who a lethal form of the disease, defined as metastatic (i.e., which has spread beyond the prostate, at which point 5-year survival rates drop to 28%) or that resulted in death. This is a slow-growing cancer – 99% of men are alive after 5 years and 98% after 10 – in spite of which 25,000 men die of the disease every year.

The study found that men who took aspirin three times a day had a 24% decreased risk of developing lethal prostate cancer after being diagnosed with an early stage of the disease, and a 39% lower risk of dying from the condition. However, aspirin had no bearing on whether or not the subjects developed prostate cancer. “Regular aspirin intake may inhibit lethal prostate cancer, probably by preventing cancer progression,” lead author of the study and a urologic oncology fellow at Harvard Medical School Dr. Christopher Allard said during a press briefing preceding GuCS. “Men with prostate cancer who took aspirin regularly after diagnosis had a significantly reduced risk of death.”  Nevertheless, he told the Wall Street Journal that “it was after diagnosis of prostate cancer that there appeared to be a benefit. It doesn’t affect the incidence, but it affects the progression.”

Dr. Allard hypothesized that the platelet-inhibiting properties of aspirin may help stop tumor cells from spreading to the bones. But given the limitations of the study the findings should not be construed as definite proof that aspirin can protect against the development or progression of prostate cancer. American Society of Clinical Oncology spokesperson Dr. Sumanta Pal brought attention to these limitations. “While this work is provocative, it is important to keep in mind that the findings are from an observational study, where surveys and reviews of hospital records were used obtain information,” he said. “These studies are certainly thought provoking but are perhaps best followed by clinical trials where we compare use of aspirin to either no treatment or perhaps to a placebo. It's also critical to keep in mind that aspirin can have some potentially severe consequences, such as bleeding. With those caveats in mind, it's important to have a detailed discussion of the pros and cons of aspirin therapy with your own physician prior to using the drug for prostate cancer-related purposes.”

Aspirin is mainly used to manage pain, inflammation, and fever, but growing evidence suggests that it may also help in the treatment or prevention of breast and colon cancer, as heart disease. On the other hand, it has also been linked to gastrointestinal adverse effects. Even though aspirin is one of the most used and available over the counter medicines – for example at Discount Medical Supplies – you shouldn’t just pop it into your mouth like Mentos, especially for purposes other than those for which it is designed. “More work is needed to identify particular subsets of men most likely to benefit from aspirin and to determine the optimal aspirin dose,” Allard said. “Men should always consult their physician before considering aspirin use.”

Related: Can aspirin cause strokes rather than prevent them?