Low-Dose Aspirin and Cancer Prevention in Older Adults
New analysis from the ASPREE study explores who may benefit—or be harmed—by daily aspirin use for cancer prevention.
A secondary analysis of the ASPREE trial suggests that low-dose aspirin may reduce cancer risk in certain older adults but increase it in others, pointing toward a complex, individualized relationship between aspirin, aging, and cancer biology.
Study Details:
The ASPREE (Aspirin in Reducing Events in the Elderly) trial originally enrolled over 19,000 adults aged 65 and older to evaluate the long-term effects of low-dose aspirin (100 mg/day) versus placebo on health outcomes.
While the primary analysis showed no overall difference in cancer rates between the two groups, researchers from Monash University reanalyzed the data to determine if certain subgroups might experience distinct benefits or risks from aspirin use.
This new analysis focused on 9,350 participants (median age 73.7 years), dividing them into “treatment-favorable” and “treatment-unfavorable” groups using a predictive model based on factors such as age, smoking status, BMI, family history of cancer, and a specific age-related blood condition known as clonal hematopoiesis of indeterminate potential (CHIP).
Methodology:
Researchers used a validated model to predict who would likely benefit or be harmed by low-dose aspirin for cancer prevention. The presence of CHIP with a variant allele frequency ≥10% emerged as the strongest indicator of benefit. CHIP involves genetic mutations in blood-forming stem cells that can increase risks for heart disease and blood cancers.
The trial tracked cancer incidence over a median of 4.6 years, comparing outcomes between aspirin and placebo groups within each subgroup.
Key Findings:
Across all participants, 10.6% in the aspirin group and 11% in the placebo group developed cancer.
59.1% of participants fell into the treatment-favorable subgroup; 40.9% were in the unfavorable subgroup.
In the favorable subgroup, aspirin was linked to a 15% lower risk of cancer (HR 0.85; 95% CI 0.71–1.00).
In the unfavorable subgroup, aspirin was linked to a 14% higher cancer risk (HR 1.14; 95% CI 0.95–1.38).
The findings showed statistically significant heterogeneity (P = .02), meaning aspirin’s impact differed meaningfully between subgroups.
However, experts cautioned that these findings stem from a secondary analysis and should be viewed as hypothesis-generating, not definitive.
Implications for Practice:
For clinicians, this analysis underscores the growing challenge of applying personalized prevention in older adults. While aspirin remains a low-cost tool with known benefits for heart health and colorectal cancer prevention, it may not be universally safe for all.
Patients with CHIP or strong family histories of cancer could be potential beneficiaries, but this needs confirmation in dedicated trials.
Routine genetic or blood-based screening for CHIP before prescribing aspirin is not yet recommended.
Importantly, past analyses from the same trial (ASPREE 2018) showed higher overall mortality, largely from cancer deaths, in those on daily aspirin.
Until further research clarifies who benefits most, doctors are advised to consider individual risk factors and age-related vulnerabilities before recommending daily aspirin for cancer prevention.