Monash Research: Aspirin Ineffective for Cancer Risk Reduction in Older Adults – JAMA Oncology Findings

The Groundbreaking Monash Findings on Aspirin and Cancer

Recent research from Monash University's School of Public Health and Preventive Medicine has delivered a significant update on the use of low-dose aspirin for cancer prevention in older adults. Published in the prestigious JAMA Oncology on January 29, 2026, the study analyzed long-term data from over 19,000 healthy seniors and found no reduction in cancer incidence from daily 100mg aspirin, with a notable 15% increase in cancer mortality during the treatment phase.5049 This challenges earlier optimism from middle-aged population studies and underscores the importance of age-specific evidence in preventive strategies.

Aspirin, or acetylsalicylic acid (ASA), has long been touted for its anti-inflammatory and anti-platelet properties, potentially inhibiting cancer development by reducing chronic inflammation and tumor growth. However, as populations age, the balance of benefits and risks shifts dramatically, particularly for primary prevention in those without prior disease.

Unpacking the ASPREE Trial: Origins and Design

The Aspirin in Reducing Events in the Elderly (ASPREE) trial, led by Monash University researchers including Professor John J. McNeil, was a landmark randomized, double-blind, placebo-controlled study launched in 2010. It enrolled 19,114 community-dwelling older adults—16,703 from Australia and 2,411 from the US—who were aged 70 years and older (or 65 for US minorities), free from cardiovascular disease (CVD), dementia, or significant physical disability at baseline.109

Participants received either 100mg enteric-coated aspirin daily or matching placebo for a median of 4.7 years (2010-2017). The trial's extension, ASPREE-XT (2018-2024), followed participants observationally after stopping study drugs, providing up to 10 years of data (median 8.6 years). Mean age at entry was 75.1 years, with 56.4% female. Outcomes were rigorously adjudicated, including incident cancers by type, stage (1-4), and metastatic status, plus cancer mortality.50

Core Results: No Incidence Benefit, Elevated Mortality Risk

The study's primary revelation: low-dose aspirin (LDA) showed no association with reduced overall cancer incidence (hazard ratio [HR] 0.98, 95% confidence interval [CI] 0.92-1.05). This held across cancer stages, metastatic vs non-metastatic, and specific types like colorectal cancer (HR 1.01, 95% CI 0.84-1.21). Over the full period, 3,448 incident cancers and 1,173 cancer deaths occurred.50

• Cancer incidence: Neutral effect (HR 0.98).
• Cancer mortality during RCT phase: 15% higher (HR 1.15, 95% CI 1.03-1.29).
• Post-RCT legacy effect: No difference (HR 1.02, 95% CI 0.83-1.25).

Lead author Associate Professor Suzanne G. Orchard noted, “Whilst we found overall no change in cancer incidence risk with aspirin when initiated in older age, we found cancer mortality remained significantly elevated by 15 per cent.”49

Why Prior Optimism Doesn't Translate to Older Age

Earlier observational and trial data from middle-aged adults (40-60s) suggested long-term aspirin (10+ years) cuts colorectal cancer risk by 20-40% and overall cancer by ~10-20%, via mechanisms like COX-2 inhibition reducing polyps. Meta-analyses of trials like Women's Health Study and Physicians' Health Study supported this for sustained use starting younger.52

However, ASPREE's older cohort—starting late in life—reveals a different picture. Short intervention duration relative to cancer latency, higher bleeding vulnerability, and possible promotion of advanced disease progression explain the divergence. Previous ASPREE analyses (2021) hinted at more late-stage cancers with aspirin.116

Australian Context: Cancer Burden in Seniors

In Australia, cancer is the leading cause of death for those 75+, accounting for ~30% of mortality. AIHW data projects 2025 age-standardized cancer mortality at 194 per 100,000 overall, but crude rates soar in 70+: incidence peaks at 80-84 years (over 2,500/100,000). Colorectal, prostate, lung, and breast dominate.71 Low-dose aspirin prevalence among healthy 70+ is ~20-30%, often for CVD prevention, but ASPREE shifted guidelines away from routine use.

Monash's findings resonate locally, where ~50,000 annual cancer deaths occur, many preventable via screening like National Bowel Cancer Screening Program rather than aspirin.AIHW Cancer Data

Monash Researchers' Insights and Recommendations

Assoc Prof Orchard emphasized: “From these findings, commencing a program of low-dose aspirin for a number of years for the prevention of cancer is not recommended in older adults. Individuals who are concerned about their cancer risk should speak to their doctors about the right strategy for their individual health care.”49 The team calls for longer ASPREE-XT follow-up to clarify transient mortality signals.

Cancer Council Australia aligns, advising against aspirin for colorectal prevention over 70 due to bleeding risks outweighing benefits.

Current Guidelines and Clinical Shifts

Australian RACGP and Heart Foundation post-ASPREE recommend against initiating LDA for primary CVD prevention in 70+, mirroring USUSPSTF. Cancer Council endorses consideration for 50-70 at average risk but cautions bleeding (gastrointestinal 2-3x higher in elderly). Personalized approaches, like genetic risk or clonal hematopoiesis (CHIP), may identify aspirin responders per 2025 ASPREE subgroup analysis.10470

Monash's Global Impact in Public Health Research

Monash's School of Public Health and Preventive Medicine (SPHPM), Australia's largest, publishes ~900 papers yearly, leading trials like ASPREE that influence WHO policies. Their biostatistics, epidemiology expertise drives evidence changing practice. For aspiring researchers, SPHPM offers PhD programs in preventive medicine, fostering careers in clinical trials.Explore research jobs at universities like Monash.81

Career Pathways in Cancer Prevention Research

This study exemplifies opportunities in higher ed for epidemiologists, biostatisticians. Roles like research assistants analyze trial data, advancing to professorships. Australia needs experts amid rising chronic disease.Tips for research assistants. View openings.

• Skills: SAS/R stats, trial design.
• Prospects: NHMRC-funded postdocs.
• Aus focus: Aging population research booming.

Future Outlook: Personalized Prevention Strategies

Emerging: AI-driven risk models, CHIP screening for aspirin benefit. Monash's ongoing ASPREE-XT and cohorts like Health2000 track legacy effects. Alternatives: Lifestyle (diet, exercise cuts CRC 30%), vaccines (HPV), screening. Optimism for precision oncology reducing senior mortality.Full JAMA Oncology paper50

Actionable Advice for Older Adults and Clinicians

Consult GPs before starting/stopping aspirin; prioritize evidence-based screening. Researchers: Join trials via higher ed jobs. AcademicJobs.com connects to roles shaping tomorrow's health policies.