Researchers have discovered in a new study published in the August 10 edition of the Journal of the National Cancer Institute, that even though taking aspirin on a daily basis is linked to lower overall cancer mortality, this association may be smaller than previously thought.

According to a recent meta-analysis of randomized trials that investigated the effects of daily aspirin use as a preventive measure for vascular events, overall cancer mortality was considerably lower (37%) after a 5-year follow-up and by 15% after a ten-year follow-up. However, regardless of these outcomes, there is still insufficient knowledge regarding the effects of long-term daily aspirin use on cancer mortality.

To investigate further, Eric J. Jacobs, Ph.D., of the Epidemiology Research Program at the American Cancer Society in Atlanta and his team evaluated data of 100,139 men and women from the Cancer Prevention Study II Nutrition Cohort with no prior cancer history, who had been taking a daily dose of aspirin. To establish the participants’ aspirin intake they used follow-up questionnaires.

They discovered that daily usage of aspirin in 5,138 patients was associated with slightly lower cancer mortality and was not related to the period these patients took daily aspirin. The team writes:

“Our results are consistent with an association between recent daily aspirin use and modestly lower cancer mortality.” Even though the meta-analysis showed a 16% lower estimated reduced risk, which was significantly lower than observed during the five-year follow-up period, the team still writes: “Even a relatively modest benefit with respect to overall cancer mortality could still meaningfully influence the balances of risk and benefits of prophylactic aspirin use.”

The team highlights that their study has potential limitations due to the fact that it was an observational study, and not a randomized trial. They could have therefore either under- or overestimated the size of reduction in cancer mortality from aspirin usage due to confounding factors.

John A. Baron, M.D., of the Department of Medicine at the University of North Carolina School of Medicine writes in a linked editorial that study outcome reinforces the hypothesis of an existing link between daily aspirin use and reduced cancer mortality, writing: “The drug clearly reduces the incidence and mortality from luminal gastrointestinal cancers, and it may similarly affect other cancers.” He notes that the findings from the American Cancer Society study might be “conservative.”

He concluded: “As for any preventative intervention, the benefits must be balanced against the risks, particularly when the benefits are delayed whereas the risks are not.”

Written by Petra Rattue