In a new study, researchers found that for older adults with advanced cancer, initiating aspirin may increase their risk of disease progression and early death.
The research was conducted by a team at Massachusetts General Hospital (MGH) and elsewhere.
Previous studies have shown that in middle-aged adults, aspirin may reduce the risk of developing cancer, especially colorectal cancer.
Information is lacking for older adults, however.
In the study, the team did the first randomized double-blind placebo-controlled trial of daily low-dose aspirin (100 mg) in otherwise healthy older adults.
The study included 19,114 Australian and U.S. community-dwelling participants aged 70+ years without heart disease, dementia, or physical disability at the start of the study.
Participants were assigned to aspirin or placebo and followed for about 5 years.
In October 2018, the team published a very surprising and concerning report showing an association between aspirin use and an elevated risk of death, primarily due to cancer.
The current report now provides a more comprehensive analysis of the cancer-related effects of aspirin.
The team reported that 981 participants who were taking aspirin and 952 who were taking placebo developed cancer.
There was no big difference between the groups for developing cancer overall or for developing specific types of cancer.
Aspirin was linked to a 19% higher risk of being diagnosed with cancer that had spread (or metastasized) and a 22% higher risk of being diagnosed with stage 4, or advanced, cancer, however.
Also, among participants who were diagnosed with advanced cancer, those taking aspirin had a higher risk of dying during follow-up than those taking placebo.
Deaths were particularly high among those on aspirin who were diagnosed with advanced solid cancers, suggesting a possible adverse effect of aspirin on the growth of cancers once they have already developed in older adults.
They added that the findings suggest the possibility that aspirin might act differently, at the cellular or molecular level, in older people, which requires further study.
One author of the study is Andrew T. Chan, MD, MPH, Chief of the Clinical and Translational Epidemiology Unit at MGH.
The study is published in the Journal of the National Cancer Institute.
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