The longstanding belief that daily aspirin intake could serve as a preventive measure against cancer in older adults has been challenged by recent findings. The ASPREE-XT study, an extension of the original ASPREE trial, reveals that prolonged use of low-dose aspirin does not reduce cancer incidence among the elderly.
The ASPREE trial initially indicated no significant difference in cancer rates between those taking aspirin and those on a placebo over a median follow-up of 4.7 years. Now, with an extended observation period of 8.6 years, the ASPREE-XT study confirms these findings, showing no association between aspirin use and overall cancer incidence in older adults.
New Insights from ASPREE-XT
Associate Professor Suzanne Orchard, the director of the ASPREE-XT study, expressed her surprise at the results. “Given the longer follow-up, we thought that would be a long enough timeframe to see if anything had changed,” she stated. “But we didn’t see any change in cancer incidence rates over the long-term.”
The follow-up study, published in JAMA Oncology, involved over 14,000 participants who remained cancer-free at the end of the original ASPREE study. During the ASPREE-XT phase, 3,448 new cancer cases were detected, alongside 1,173 cancer-related deaths. However, the hazard ratio for overall cancer incidence was 0.98, with a 95% confidence interval of 0.92-1.05, indicating no significant protective effect from aspirin.
“Whilst we did still see the elevated cancer-related mortality risk – it was lower than it was at the end of the clinical trial phase, it had dropped down to 15% – when we restricted our analysis to the follow-up phase where participants weren’t taking the study medication, we didn’t see any cancer-related mortality risk at all,” said Professor Orchard.
Implications for Aspirin Use in Older Adults
Despite the lack of evidence supporting aspirin’s role in cancer prevention, the study did note a potentially protective effect against melanoma, with a hazard ratio of 0.77. However, aspirin was associated with a 15% increased risk of death following an incident cancer event, a finding that contrasts with the original ASPREE trial, which linked aspirin to a higher risk of stage 4 cancer incidence.
Professor Orchard emphasized that the results should not prompt individuals prescribed aspirin for secondary prevention to cease their medication without consulting their healthcare provider. The study’s findings specifically pertain to older adults initiating aspirin for primary cancer prevention.
Historical Context and Changing Guidelines
The ASPREE and ASPREE-XT studies are part of a broader body of research examining aspirin’s effects on various health outcomes. Over the past decade, evidence has suggested that daily low-dose aspirin does not promote a healthy lifespan or reduce all-cause mortality in older adults. In fact, it has been associated with increased risks of intracranial bleeding, serious falls, and major gastrointestinal bleeding.
In light of these findings, major health organizations are revising their guidelines. The Australian Cancer Council has adjusted its recommendations, advising that individuals over 70 discuss aspirin use with their clinicians. Similarly, the United States Preventive Services Task Force withdrew its recommendation for aspirin use in colorectal cancer prevention for those over 70, citing a lack of benefit and potential risks.
“The main take-home message is that just because aspirin works in a middle-aged cohort in a particular way doesn’t mean it’s going to work the same way in an older person,” Professor Orchard noted.
Future Research Directions
Plans for further research are already in motion. The ASPREE-LT study, funded by the National Cancer Institute in the US, will extend the follow-up period to over 15 years, aiming to provide more definitive evidence on aspirin’s long-term effects. This phase will involve annual health check-ins with participants to gather comprehensive data.
While the current study has not established a protective role for aspirin in cancer prevention among older adults, it underscores the importance of personalized medical advice and the need for ongoing research to clarify aspirin’s role in different age groups and health contexts.
