Daily Aspirin Fails to Prevent Cancer in Older Adults, May Increase Mortality Risk
Landmark new research has delivered a significant blow to previous suggestions that daily low-dose aspirin could help prevent cancer in later life. A comprehensive Australian study has found that not only does the common over-the-counter painkiller fail to provide protective benefits against cancer when started in old age, but it may actually increase the risk of dying from the disease.
The Global Context of Age-Related Cancer
Globally, aging populations have led to a marked increase in the prevalence of age-related disorders, with cancer being a primary concern. Statistics reveal that approximately two-thirds of all new cancer cases are diagnosed in individuals aged 60 and older, highlighting the urgent need for effective preventive strategies in this demographic.
For years, various studies had hinted at potential anticancer properties of aspirin, suggesting it might lower the risk of developing certain cancers—particularly bowel cancer—slow their spread, and even reduce mortality rates. These claims have now been robustly challenged by the latest findings from Australian researchers.
Study Design and Participant Profile
The research, published in the prestigious JAMA Oncology journal, involved a randomised controlled trial with over 19,100 adults aged 70 and above. Participants were prescribed either a daily 100mg aspirin tablet or a matching placebo for a period of just over four and a half years.
At the study's commencement, all participants were free from diagnosed heart disease and dementia, and were capable of living largely independently. While a history of cancer was not an exclusion criterion, doctors assessed that all individuals involved had a life expectancy of at least five years.
Concerning Results on Cancer Incidence and Mortality
Throughout the trial, researchers recorded 3,448 cancer cases and 1,173 cancer-related deaths among participants. Analysis conducted 8.5 years later revealed that taking aspirin for the study duration had no measurable impact on overall cancer risk.
More alarmingly, the data showed that participants who took aspirin daily and subsequently developed cancer were 15 per cent more likely to die from the disease compared to those who received placebo pills. This elevated mortality risk represents a significant finding that contradicts previous optimistic assumptions about aspirin's protective effects.
Detailed Analysis and Subgroup Findings
Among the 14,907 participants who did not develop cancer during the study period, researchers found no major differences between treatment groups regarding factors such as age, sex, body weight, smoking status, alcohol use, and family history.
The research team also investigated aspirin's effects according to cancer stage at diagnosis. Their analysis revealed that aspirin use was associated with an increased risk of stage four cancer—indicating the disease had already metastasised to another organ by the time of diagnosis.
Researchers' Conclusions and Caveats
The study authors concluded: 'We found overall no cancer incidence benefit with aspirin when initiated in older age, but cancer mortality risk remained significantly elevated, although longer follow-up of the cohort is warranted.'
Interestingly, while researchers observed an increase in cancer mortality risk linked to aspirin use during the trial, this effect did not persist into the post-trial follow-up period, suggesting no legacy or carry-over effect from the medication.
The Melanoma Exception and Further Research Directions
One intriguing exception emerged regarding melanoma—the fifth most common cancer in the UK. The study suggested aspirin might have a long-term protective effect against this particular cancer, though researchers emphasise this finding warrants further investigation.
This potential exception is particularly relevant for Australia, where high levels of sun exposure to harmful UV rays contribute to melanoma rates. Approximately 15,000 Britons and 100,000 Americans are diagnosed with melanoma annually, with incidence rising faster than any other common cancer.
Understanding Melanoma's Characteristics and Risks
Melanoma develops when DNA in skin cells becomes damaged, triggering mutations that lead to cancerous growth. The disease is often fast-growing and can quickly penetrate through skin layers into underlying blood vessels. Once cancer cells enter the bloodstream, the disease can spread throughout the body.
Despite significant treatment advances that have improved survival rates from less than 50 percent to over 90 percent in the past decade, melanoma still claims more than 2,000 lives annually in the UK alone. Increased UV exposure from both natural sunlight and tanning beds has been identified as a primary driver of rising melanoma cases.
The research team's findings represent a substantial shift in understanding about aspirin's role in cancer prevention for older adults. Medical experts now caution against recommending daily aspirin specifically for cancer prevention in this age group, given the potential for increased mortality risk without corresponding protective benefits.
