Nick Mulcahy

April 06, 2017

WASHINGTON, DC — Long-term, regular aspirin use was associated with both a reduced relative risk for death from any cause and also death from cancer,  according to a new observational study involving more than 130,000 health professionals.

Overall mortality risk was 7% lower for women and 11% lower for men who regularly used aspirin compared with nonregular aspirin users. And cancer mortality risk was 7% lower for women and 15% lower for men who regularly used aspirin.

The median follow-up time was 32 years.

The new results were reported by  Yin Cao, MPH, ScD, from the Massachusetts General Hospital in Boston, and colleagues in a presentation here at the American Association for Cancer Research (AACR) 2017 Annual Meeting.

Aspirin was beneficial at doses of at least 0.5 to 1.5 standard tablets per week for both men and women. The minimum duration of regular use associated with lower cancer mortality was 6 years, the authors note..

"The reductions in the risk of cancer death may seem modest but the effect size is comparable to the increase in the risk of cancer death associated with obesity," Dr Cao told Medscape Medical News.

The team studied 86,206 women enrolled in the Nurses' Health Study between 1980 and 2012, and 43,977 men enrolled in the Health Professionals Follow-Up Study between 1986 and 2012. In each study, aspirin use was assessed at baseline and every 2 years afterward.

"It's compelling data," said Manish Shah, MD, a gastrointestinal oncologist at Weill Cornell Medicine and New York-Presbyterian Hospital in New York City.

However, Dr Shah, who was not involved in the study, also observed that the gold standard of evidence is a prospective, randomized trial.

"These kind of cohort analyses can have significant biases," he said. "Part of the effect may be due to the fact that aspirin users may be more health conscious overall."

Aspirin users may be more health conscious overall. Dr Manish Shah

The new research was inspired by a number of findings and events in recent years, said Dr Cao.

For example, there was a major event in preventive medicine in September 2015, when the US Preventive Services Task Force (USPSTF) recommended that adults 50 to 69 years of age should take daily low-dose aspirin for at least 10 years to reduce their risk for cardiovascular disease and colorectal cancer.

That recommendation was based on clinical trials, which did not reveal the potential population-wide effect of aspirin use on cancer.

So, in 2016, Dr Cao and colleagues published a cancer incidence study using these same two large cohorts that showed long-term aspirin use was associated with a modest but significantly reduced risk for overall cancer.

The new study sought to once again look at a population-wide effect, but on mortality (not incidence), and addresses a question that arises from the USPSTF recommendation, said Dr Cao.

"The question is if you use aspirin for the prevention of cardiovascular disease and colorectal cancer, would you then get some additional benefit in the future in terms of reducing mortality risk with other cancers," she said.

The new study suggests that yes, there might be additional benefit.

During the follow-up period, 8271 women and 4591 men died of cancer. Compared with nonregular use, regular aspirin use was associated with about a 30% lower risk of dying from colorectal cancers (for both sexes), 11% lower risk from breast cancers, 23% lower risk from prostate cancers, and 14% lower risk from lung cancers in men.

Using aspirin for the prevention of cardiovascular disease and colorectal cancer carries risks. The two mentioned most prominently are gastrointestinal (GI) bleeding and hemorrhagic stroke.

Dr Yao points out that the USPSTF recommendation about aspirin was based on decision analyses that only looked at the risks and benefits found in colorectal cancer and cardiovascular disease data.

She would like to see further decision analyses that "attempt to capture additional benefit with aspirin use," which would in turn be balanced against the potential risks of GI bleeding, stroke, and other adverse events.

This study was supported the National Institutes of Health. Dr Cao and Dr Shah have disclosed no relevant financial relationships.

American Association for Cancer Research (AACR) 2017 Annual Meeting. Abstract 3012. Presented April 3, 2017.

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