Aspirin. Windex. Robitussin. (Or in my house, iodine.) Earlier this week, scientists revealed that one of these household heal-alls helped reduce deaths from a variety of common cancers – but don’t start popping those pills every day just yet, doctors caution.
Oxford’s Peter Rothwell and his colleagues wanted to see what else it could do. “There’s been a lot of work over the years showing that certain compounds can increase the risk of cancer,” he says, “but it’s not been shown before that we can reduce the risk with something as simple as aspirin.”
They examined data on patients from 8 randomized trials originally designed to look at aspirin and heart disease – which involved 25,570 people (and 674 cancer-related deaths). For many of the subjects, the researchers found records that spanned 20 years after the trials.
People who received an aspirin a day were 20% less likely to have died of cancer than people in the control 'no aspirin' groups two decades later:
- Esophageal cancer deaths were cut by 60%
- Colorectal cancer deaths were reduced by 40%
- Gastrointestinal cancer deaths decreased by 35%
- Lung cancer deaths were reduced by 30%
- Prostate cancer deaths were lowered by 10%
The benefits were unrelated to dose (75 mg upwards, even a baby aspirin will do), sex, or smoking – but they did go up with age: “The benefit increased quite steeply with the length of time people were on it,” Rothwell says.
But researchers are not exactly sure how it works. In the test tube, when cells divide, there is a chance the DNA in the new cells will be faulty. Healthy cells will recognize those defects and either repair them or cause the defective cells to self-destruct, says co-author Tom Meade of the University of London. “Both mechanisms are enhanced by aspirin.”
Aspirin's effect on cancer, Rothwell says, is a lot bigger than its benefit in preventing heart attacks and strokes – the reason millions of Americans already swallow a baby aspirin (81 mg) a day.
Rothwell himself takes an aspirin every day, adding that the sensible time to start taking it would be before the risk of cancer starts to rise, at about age 45.
But aspirin carries risks, so doctors are unready to go recommending aspirin to everyone over a certain age. A daily dose of aspirin increases the risk of ulcers and nearly doubles the risk of internal bleeding. “So the increased risk of bleeding is about 1 in 1,000 per year, while the decreased risk of cancer is 2, 3 or 4 per 1,000 per year,” Rothwell argues.
But by anyone’s measure, aspirin is a bargain, as the Economist reports: Taking it for 5 to 10 years easily beats initiatives to screen for breast and prostate cancers. To put it another way, ask yourself what a pharmaceuticals firm might charge for a drug that would reduce the chance of death by cancer by 20% – and then note that 100 days’ supply of low-dose aspirin can cost less than a dollar.
The study was published in the Lancet earlier this week.
Image by jellywatson via Flickr