PerspectiveIn the Journals

Long-term aspirin use reduced risk for cancer, cardiovascular events

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August 14, 2014

Average-risk adults must adhere to a daily prophylactic aspirin regimen for 5 years to derive its protective benefits against cancer, myocardial infarction and stroke, according to an evidence review.

Individuals aged 50 to 65 years who use prophylactic aspirin in doses of 75 to 325 mg per day for 10 years would benefit even more, with the relative risk for cancer and cardiovascular events dropping by 7% among women and 9% among men over a 15-year period, results showed. Researchers’ conservative estimates of absolute risk reductions — which are sex and age dependent — ranged from 0.68% to 3.09%. Also, these individuals would derive an overall 4% relative reduction in deaths from any cause over a 20-year period, according to researchers.

Reduced risk for colorectal, esophageal, gastric, lung, prostate and breast cancers accounted for 61% to 80% of the benefit derived from aspirin use.

Jack Cuzick

“We wrote a paper in 2009 published in The Lancet Oncology saying [aspirin use] was promising but further follow-up of the ongoing studies was needed,” Jack Cuzick, PhD, head of the Cancer Research UK Centre for Cancer Prevention and director of the Wolfson Institute of Preventive Medicine at Queen Mary University of London, told HemOnc Today. “That has now occurred and the results are very clear. We have now done a comprehensive analysis of benefits and harms and concluded that for most men and women aged 50 years to 65 years, the benefits of a daily low-dose aspirin strongly outweigh the risks, which are primarily stomach and bowel bleeding.”

Cuzick and colleagues evaluated data from recent systematic reviews and individual studies that assessed the benefits and harms associated with aspirin.

Researchers’ best estimates of the combined data indicated aspirin was associated with reduced incidence and mortality of colorectal cancer (incidence risk ratio, 0.65; mortality risk ratio, 0.6), esophageal cancer (incidence risk ratio, 0.7; mortality risk ratio, 0.5), gastric cancer (incidence risk ratio, 0.7; mortality risk ratio, 0.65), lung cancer (incidence risk ratio, 0.95; mortality risk ratio, 0.85), prostate cancer (incidence risk ratio, 0.9; mortality risk ratio 0.85) and breast cancer (incidence risk ratio, 0.9; mortality risk ratio, 0.95).

Aspirin also was associated with a reduced risk for myocardial infarction incidence (risk ratio, 0.82) and mortality (risk ratio, 0.95), as well as stroke incidence (risk ratio, 0.95).

However, aspirin was associated with increased incidence of major extracranial bleeding (risk ratio, 1.54), as well as mortality from gastrointestinal bleeding (risk ratio, 1.6) and peptic ulcers (risk ratio, 1.6).

Data showed a 0.16% to 0.81% increase in absolute major bleeding rates from baseline rates associated with aspirin, and this risk increased with age.

Using these data, researchers calculated a 6% net benefit of aspirin use for men and women in the general population.

The benefits associated with aspirin commenced after 3 years of use, although researchers were unable to draw conclusions on the difference of effects between low or standard aspirin doses.

“A few people are at higher risk of bleeding, so individuals should discuss this with their doctor before starting regular daily baby aspirin,” Cuzick said. “Usage needs to be for at least 5 years, and we recommend 10 years.”

Disclosure: The researchers report consultant, advisory board or medical director roles with; research funding or honoraria from; and stock ownership in AstraZeneca, Bayer Pharma, Biotronic, Boehringer Ingelheim, Dr Falk Pharmaceuticals, Johnson & Johnson, QuantuMDx, Sanofi/Bristol-Myers Squibb and Servier. Researchers also report executive committee service or chief investigator roles with the ARRIVE, AspECT and ChoPIN trials.

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Emily Chan

Emily Chan

The review by Cuzick and colleagues summarizes updated data regarding the role of aspirin in reducing cancer incidence and mortality in the general population. They conclude that aspirin use of 75 mg to 325 mg daily for at least 5 years results in a favorable risk–benefit profile with regard to a reduction in cancer incidence and mortality for several cancers.
Although the results that they report are impressive, they excluded uncomplicated peptic ulcers and other minor bleeding events from the analysis, and clinicians and researchers need to bear this in mind when interpreting these results.
These data do not support daily aspirin usage in everyone, but they do support an individualized discussion regarding aspirin usage with patients, taking into account the risks and benefits of daily aspirin usage with the patient’s co-morbidities and risks for cancer. These conversations also should incorporate discussions about the impact of lifestyle modifications in areas such as diet, weight, exercise and smoking cessation with regard to general health.  
Further studies with aspirin should include identification of predictive biomarkers to determine who may best benefit from aspirin usage.

Emily Chan, MD, PhD
Assistant professor of medicine Vanderbilt-Ingram Cancer Center

Disclosure: Chan reports no relevant financial disclosures.