Aspirin has multiple benefits. It is a painkiller whose origins can be traced to Hippocrates, reduces the chances of developing or dying from cancer earlier than previously thought and also prevents tumors from spreading, studies show.
People who took a daily dose of aspirin had a 24 percent lower rate of developing cancer after three years and were 37 percent less likely to die from the disease after five years than those who didn't, according to a study in The Lancet medical journal. The rate was similar for men and women.
It is known since 2007 that aspirin can reduce the long-term risk of dying from cancer, though those benefits are only seen after at least eight years. The new studies show the drug also has short-term advantages, suggesting it could be used to treat some tumors, said Peter Rothwell, a professor at the University of Oxford who led the research. “Aspirin differs from virtually all other drugs in that situation, both in the sense that it's considerably cheaper, but also it's probably a lot safer,” Rothwell said.
Cancer is the second most common cause of premature death worldwide and 5 million new cases are diagnosed in Europe and the U.S. each year, Rothwell and colleagues wrote. The risk of the disease starts to increase “steeply” from about age 45, suggesting that might be a good time to start taking aspirin, Rothwell said. The risk of internal bleeding from aspirin increases from about age 65, which would be a good time to stop, he said.
The researchers also found that the risk of internal bleeding, a potential side-effect of aspirin, wanes over three or four years, Rothwell said. After that, the risk of dying from a bleed was lower among those taking aspirin than those who weren't, the study found.
Public health experts worry about widespread use of aspirin, because the drug increases the risk of gastrointestinal bleeding, ulcers and hemorrhagic strokes that can be fatal. Aspirin may be a household staple, but it is also a potentially toxic drug, said Dr. Khosrow Kashfi, an associate medical professor at the City College of New York, who is working to develop a safer but more potent form of aspirin. Experts urged patients to seek individualized guidance from a physician to assess personal risks and benefits.
“People with a family history of cancer in middle age, or a family history particularly of colon cancer, or people with vascular risk factors who are at risk of heart attack or stroke” would be most likely to benefit from taking aspirin, Rothwell said. “If someone's completely healthy, and has a good diet, doesn't smoke, does regular exercise, has no risk factors for cancer or for heart attacks and stroke, then the benefit will probably be greater than the risk, but the benefit will be relatively small.”
Rothwell and colleagues reviewed 51 trials involving about 78,000 people concerning the use of aspirin to prevent heart attacks and stroke. The reduction in the risk of dying from cancer was probably because aspirin prevents tumors from spreading, he said. Two other studies published in The Lancet and The Lancet Oncology showed that aspirin reduced the risk of any cancer spreading to other organs by 36 percent and certain types of tumors by 46 percent. “We still need to do trials of aspirin in treatment of cancer to show that the benefit is definitely there if you start taking it after the cancer's been diagnosed,” Rothwell said. “But potentially it would be a highly cost-effective way of preventing the spread of cancers.”
He's now involved in a study testing aspirin to treat people with colorectal cancer, and another trial with lung cancer patients is starting, he said. The drug is already recommended for middle-aged patients at risk of heart disease or stroke, Rothwell said.
“This is an exciting development,” Peter Johnson, the chief clinician of Cancer Research UK, said in an emailed statement. “We now need some definitive advice from the government as to whether aspirin should be recommended more widely.”
Critics say the new analyses may not be reliable because they are based on data from studies that were designed to assess aspirin's effect on vascular disease, not cancer. More than 40 million U.S. adults already take an aspirin a day to prevent heart disease.