ASA for the elderly: fewer heart attacks, more cancer

Lisa Vogel studied departmental journalism with a focus on medicine and biosciences at Ansbach University and deepened her journalistic knowledge in the master's degree in multimedia information and communication. This was followed by a traineeship in the editorial team. Since September 2020 she has been writing as a freelance journalist for

More posts by Lisa Vogel All content is checked by medical journalists.

Millions of people around the world swallow acetylsalicylic acid (ASA) every day. The pain reliever thins the blood and is said to protect against heart attacks and strokes. Three different studies recently showed that taking ASA can prevent heart disease. In many cases, however, the associated risks can be more serious.

ASA thins the blood. It then forms fewer clots that can travel to the heart and brain. Risk patients are therefore often advised by their doctors to take ASA or other blood thinners in low doses as a preventive measure against heart attacks and strokes. Since ASA is freely available, even healthy people are now taking the active ingredient on their own initiative. However, three current studies show that this can be dangerous.

Do older, heart-healthy people also benefit from ASA?

"Clinical guidelines recommend ASA for the prevention of heart attacks and strokes in patients with cardiovascular diseases such as coronary artery disease," explains Richard J. Hodes of the National Institute on Aging, which supported the largest of these studies. It has so far been unclear whether ASA is also used by older people who have no previous cardiovascular diseases of this kind.

Less heart disease, more cancer deaths

To find out, scientists led by Professors John McNeil and Mark Nelson from Monas University in Melbourne evaluated the data of more than 19,000 people as part of the ASPREE study. The majority of the participants were 70 years or older and had not previously suffered from cardiovascular disease. Half of them took 100 milligrams of ASA a day for more than four years, the other half received an inactive placebo.

Fewer heart deaths ...

The scientists hoped that the administration of aspirin would lower the rate of fatal cardiovascular events - that is, fewer deaths from heart attacks, strokes and other consequences of vascular diseases. In fact, 91 subjects in the ASA group died from it during the course of the study. In the placebo group, it was almost 25 percent more at 112. This shows that the blood thinner actually has a preventive effect.

The real surprise of the study, however, was how great the risks associated with taking it were: the overall mortality in the ASA group was even higher than in the placebo group: 558 of them died. That corresponds to 5.9 percent. In the control group it was only 494 and thus 5.2 percent. Interestingly, however, this effect did not show up until the fourth year of the observation period.

... but more cancer deaths

As would be expected in an older group of participants, the leading cause of death in both groups was cancer. 295 of the ASA test subjects died of it. For comparison: 227 in the placebo group. The researchers found no evidence that a higher bleeding tendency had played a role in these deaths.

Unclear mechanisms

The reasons for the connection are still unclear. However, it is known that the active ingredient influences various signaling pathways that are involved in the development and spread of cancer, the authors write. You have kept tissue samples from the patient, with the help of which a corresponding mechanism may be uncovered at a later point in time.

Overall, the results should be interpreted with caution, the authors write. Previous studies had given the opposite results: even fewer cases of cancer had occurred under the intake of ASA. However, these studies included data from significantly fewer people. Above all, only a few sample participants who were 70 years or older took part.

More bleeding in the stomach and intestines

But what about younger risk patients? An example of this are diabetics who are more likely to develop arteriosclerosis due to their high blood sugar levels. However, prevention with ASA is not generally recommended for them either.

At least this is the conclusion reached by the ASCEND Study Collaborative Group. She analyzed the data from 15,480 diabetics. The use of aspirin resulted in less vascular disease, but increased the risk of gastrointestinal bleeding. In the eyes of the researchers, the risk of bleeding outweighed the benefits of thinning the blood.

Enjoy with caution

The use of ASA should also be used with caution for non-diabetics with only a moderate risk of cardiovascular diseases. This, in turn, is shown by the ARRIVE study by Professor Michael Gaziano of Harvard Medical School. Of 12,546 subjects, 6270 took aspirin daily and 6276 took a placebo. In the aspirin group, 61 people developed gastrointestinal bleeding, compared with less than half in the placebo group.

Blood lipids instead of blood thinners?

Statins could be an alternative to ASA. These are mainly used to treat high blood lipid levels. But they also affect the platelets, i.e. those cells in the blood that are responsible for clotting. According to the German Heart Foundation, statins reduce the risk of heart attack. The chances of survival of patients with coronary artery disease also increase under the medication.

No general end for ASS as heart protection

The researchers emphasize that the results do not apply to younger patients or those who are already at high cardiovascular risk. In particular, none of the studies questioned blood thinners for so-called secondary prevention. This affects patients who have already had a serious cardiovascular incident such as a stroke or heart attack. Anyone who is prescribed ASA by their doctor should therefore never stop using it on their own initiative.

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