A major new follow-up study has found that low-dose aspirin does not lower cancer risk in older adults. The research also shows that aspirin may increase cancer-related deaths while a person is actively taking it. These findings challenge earlier beliefs that aspirin could help prevent certain cancers, especially colorectal cancer.

This article explains the study in simple language, why the results matter, and what older adults should know before using aspirin for preventive health.

What Did the Study Find?

Researchers followed more than 19,000 older adults for nearly 9 years as part of a long-term follow-up to the ASPREE trial. The goal was to understand whether taking 100 mg of aspirin daily had any effect on cancer.

The key findings were:

• Aspirin did not reduce overall cancer risk.

• Those taking aspirin had a 15% higher risk of cancer-related death during the trial period.

• There were no long-lasting benefits or harms once participants stopped aspirin.

• The study confirmed that aspirin should not be started in older adults as a strategy to prevent cancer.

No Reduction in Total Cancer Cases

The long-term analysis recorded 3,448 new cancer cases and found no difference between the aspirin group and the placebo group. This is in contrast to some earlier studies that showed aspirin might protect younger adults from colorectal or liver cancers.

However, most earlier research involved:

• People in middle age

• People with higher cancer risk

• Follow-up periods of 10 years or more

This new study focused on older adults who began aspirin around age 74, and the outcomes were very different.

Why Did Aspirin Increase Cancer-Related Deaths?

During the ASPREE trial, those taking aspirin had more late-stage cancers and higher cancer mortality. The increased risk was only seen while participants were actively taking aspirin.

Researchers believe several age-related factors may explain this:

• Declining immune system function (immunosenescence)

• Chronic low-grade inflammation

• Differences in how tumors behave in older adults

These biological changes may weaken aspirin’s potential protective effects or even contribute to worse outcomes.

No Long-Term Harm After Stopping Aspirin

To check for delayed effects, researchers observed nearly 15,000 cancer-free participants after the main trial ended. They found:

• No ongoing increased risk of cancer

• No protective effect

• A slight reduction in metastatic cancer risk among former aspirin users, but not enough to lower deaths

This means aspirin did not create lasting harm or benefit after discontinuation.

Are There Any Exceptions?

A few findings stood out, but they were not strong enough to guide medical decisions:

Possible Lower Risk of Melanoma

Aspirin users had fewer melanoma cases over the long term. However:

• The number of cases was small

• Results may be due to chance

• More research is needed

Higher Rates of Rare Cancers

Some rare cancers and brain cancers appeared slightly more often in the aspirin group, but again, the numbers were small and not conclusive.

What Should Older Adults Do?

Based on current evidence:

• Do not start low-dose aspirin solely to prevent cancer if you are 60 or older.

• Aspirin can still be beneficial for specific heart-related conditions, but only under medical supervision.

• Guidelines already advise not beginning aspirin after age 60 for primary prevention of chronic disease.

Anyone currently taking aspirin for heart health should not stop without speaking to their doctor.

Why This Study Matters

As global populations age, cancer becomes more common. Many people look for simple preventive strategies, and aspirin has long been considered a low-cost option.

However, this large and carefully conducted study shows:

• Aspirin’s effects vary with age

• Benefits seen in younger adults do not apply to older age groups

• Starting aspirin late in life may do more harm than good when it comes to cancer outcomes

Long-term monitoring of the study participants will continue for up to 15 years, which may offer more insights in the future.

Conclusion

Low-dose aspirin should not be recommended as a cancer-prevention tool for older adults. While it may have benefits for heart disease in some individuals, its routine use for preventing cancer is not supported by current evidence.

Older adults should always discuss aspirin use with their healthcare provider to understand their personal benefits and risks.