Researchers estimate that daily aspirin use for 5-10 years could provide a 9% reduction in the number of cancers, strokes and heart attacks in men, and a 7% reduction in women.
The research team, led by Prof. Jack Cuzick, head of the Centre for Cancer Prevention at the Queen Mary University of London in the UK, recently published their findings in the journal Annals of Oncology.
Aspirin, also known as acetlylsalicylic acid (ASA), is a salicylate drug commonly used to reduce minor aches and pains, inflammation and fever. In long-term low doses, the drug is also used as an antiplatelet for patients at high risk of heart attack and stroke.
There has been much debate surrounding the benefits of long-term aspirin therapy. Previous studies have suggested it can reduce risk of ovarian cancer and improve colon cancer survival, while others claim it can cause harm, with one study suggesting it increases the risk of age-related macular degeneration.
In this latest research, Prof. Cuzick and his team set out to determine whether the health benefits of continued aspirin use outweigh the risks.
Taking daily aspirin 'important for reducing cancer risk'
To reach their findings, the team conducted an analysis of all available evidence from an array of studies looking at the beneficial and harmful effects of aspirin use.
The researchers estimated that if individuals aged 50-65 took a daily 75-100 mg dose of aspirin for 5-10 years, the number of bowel cancer cases could be reduced by 35% and deaths by 40%, while rates of stomach and esophageal cancers could be cut by 30% and deaths by 35-50%.
Overall, they estimate that daily aspirin use for 5-10 years could provide a 9% reduction in the number of cancers, strokes and heart attacks in men, and a 7% reduction in women. Over a 20-year period, they estimate the number of deaths from all causes could be reduced by 4%. No benefits were found until individuals used aspirin for a minimum of 3 years.
But the researchers note that continued aspirin use does increase the risk of bleeding in the digestive tract. They found that individuals aged 60 who took aspirin daily for 10 years increased their risk of gastrointestinal bleeding by 1.4%, from 2.2% to 3.6%. However, they note that this is only likely to be life-threatening in around 5% of people.
"The risk of bleeding depends on a number of known factors which people need to be aware of before starting regular aspirin, and it would be advisable to consult with a doctor before embarking on daily medication," notes Prof. Cuzick.
In addition, they found that continuing aspirin use increased the risk of peptic ulcer by 30-60%.
But despite these side effects, Prof. Cuzick believes that long-term aspirin therapy could be vital to cancer prevention:
"It has long been known that aspirin - one of the cheapest and most common drugs on the market - can protect against certain types of cancer. But until our study, where we analyzed all the available evidence, it was unclear whether the pros of taking aspirin outweighed the cons.
Whilst there are some serious side effects that can't be ignored, taking aspirin daily looks to be the most important thing we can do to reduce cancer after stopping smoking and reducing obesity, and will probably be much easier to implement."
The team notes that further research is warranted to better pinpoint those who are most likely to benefit from long-term aspirin use and who is at highest risk of gastrointestinal bleeding.
Earlier this year, Medical News Today reported on a consumer update from the US Food and Drug Administration (FDA), stating that while daily low-dose aspirin use can prevent heart attack or stroke for those who have already had one, there is insufficient evidence to support its use for prevention of first-time heart attack or stroke.