Researchers in China have come out clearly against the notion that taking aspirin daily reduces the risk of bowel cancer, as reported in the Cochrane Database of Systematic Reviews.
In recent years, the use of painkillers – specifically NSAIDs (non-steroidal anti-inflammatory drugs) such as aspirin or ibuprofen – to lower bowel cancer risk has been increasingly discussed.
Since these drugs have anti-inflammatory effects, and inflammation is thought to play a role in tumour development, the hope arose that regular intake could cut bowel cancer risk.
In the United States, this was even officially recommended for a time.
However, according to the analysis published late February (2026), there is insufficient evidence for this, unlike for the risks associated with taking it.
The authors wrote that within a period of five to 15 years after starting regular intake, aspirin likely has no effect on the number of new bowel cancer cases.
They added that there may be some protective effect after 15 years, although this result is not clear and should be treated with caution, and other factors besides aspirin could also play a role.
To understand the benefits and risks of aspirin, the researchers evaluated data from around 125,000 people with an average cancer risk, drawn from 10 clinical trials mainly from Europe and North America.
In seven of the studies, a low daily dose of aspirin (75 to 100 milligrammes per day) was examined, and three assessed higher doses.
The group said it found no comparable trials in which volunteers took other similar painkillers, which is why its conclusions apply only to aspirin.
The researchers analysed how often bowel cancer occurred among participants who took aspirin daily and compared this with the share in control groups that took no aspirin or a placebo.
“While the idea of aspirin preventing bowel cancer in the long run is intriguing, our analysis shows that this benefit is not guaranteed and comes with immediate risks,” said study lead author and Sichuan University assistant professor Dr Cai Zhaolun.
The team’s evaluation showed clearly that regular aspirin intake increases the risk of bleeding in or around the brain, and the risk of stroke.
Older people and those with pre-existing conditions are particularly at risk.
The researchers emphasised that benefits and risks should therefore be weighed carefully and that people should seek medical advice.
Study co-author and Sichuan University professor Dr Cao Dan said there was no one-size-fits-all recommendation.
“The widespread use of aspirin in the general population is simply not supported by the current evidence.”
German Cancer Research Center (DKFZ) deputy division head Prof Dr Michael Hoffmeister, who was not involved in the study, said he was not surprised by the results.
He noted that there have been increasing numbers of studies with this tenor recently, and in the US, the official guideline that had previously recommended aspirin for bowel cancer prevention was changed several years ago.
With aspirin a delayed effect is known.
“That means, to see an effect, you have to take it for at least five years, and then the effect only becomes apparent in the following years.”
He added that the same applies to risks, with the risk of bleeding also rising with longer use. – dpa
