New research findings that a daily dose of aspirin can help prevent cancer throws up all sorts of questions – here are some answers
A daily dose of aspirin can reduce the risk of cancer and prevent the disease from spreading, studies show. But the drug has side effects that are serious in some patients, and health officials do not yet recommend it for healthy people.
What is aspirin?
Aspirin (acetylsalicylic acid) is an anti-inflammatory drug first used as a painkiller more than a century ago. The drug is given to people at risk of heart attacks and strokes, and patients with vascular disease. It belongs to a group of medicines known as non-steroidal anti-inflammatory drugs (NSAIDs).
How does it work?
Beyond its painkilling effects, aspirin prevents blood platelets sticking together and so thins the blood. This reduces the risk of blood clots that can cause heart attacks and stroke.
What cancer does aspirin reduce?
A small, 75mg daily dose of aspirin, taken over 10 years or so, reduces the risk of around half of cancers forming, including colorectal and oesophageal cancer, with a smaller reduction in prostate cancer and adenocarcinoma, a form of lung cancer. There seems to be no effect on kidney, bladder and lung cancers common in smokers. Aspirin taken over long periods reduced the spread of cancer through metastasis by around 50%.
How does aspirin stop cancer?
Nobody knows for sure. The drug might prevent cancer through its anti-inflammatory effects, but it may also slow the build up of mutations that ultimately lead to the cancer. The drug seems to slow the spread of disease by preventing cancer cells from being carried around the body on blood platelets.
Should everyone take aspirin?
The most serious side effect of aspirin is internal bleeding, caused when the drug damages the stomach lining. Internal bleeds can be fatal, especially in those aged 70 and older. Around 10 to 15% of people who start taking daily aspirin stop because of heartburn and other complaints, but of those who can tolerate the drug, the risk of dying from a stomach bleed is lower than normal. Peter Rothwell, whose studies at Oxford University revealed aspirin’s effect on cancer, says healthy people might start taking the drug in their mid 40s, because the risk of dying from cancer goes up steeply from the early 50s. A cancer can take 10 years to progress from tiny cellular changes to a diagnosis or death from the disease. Rothwell, who has taken 75mg aspirin a day for the past three years, advises anyone thinking of taking aspirin to discuss it with their GP first.
How much longer might a person live if they take aspirin?
Aspirin prevented around one in 30 deaths from cancer in a group that had a daily dose of aspirin for five or six years during a 20-year period. “If people took aspirin for 20 years, it would probably prolong their life by around six months on average,” says Rothwell.
Can aspirin help people with cancer?
Aspirin appears to slow the spread of cancer, but doctors need to do studies on patients to confirm how effective the drug is. “If you have a new diagnosis of cancer then, with the exception of children, I think no matter what age you are, it’s worth thinking about. The drugs you are already taking are much more dangerous than aspirin,” Rothwell said.
When was aspirin’s anticancer effect discovered?
Studies in mice in the 1960s showed that aspirin slowed the spread of cancer, but the research never made it into clinics, partly because aspirin was off patent, so companies had little to gain from funding trials.
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