Households across the country count on it to relieve headaches and joint pain, but now more evidence is emerging to suggest Aspirin could play a role in cancer prevention.
New research published Tuesday in The Lancet shows people who take low-dose Aspirin every day have significantly lower rates of being diagnosed with cancer than those who don't.
It's an important finding that could provide a major boost to cancer prevention initiatives and pave the way for changes to public health recommendations.
"We were pleasantly surprised to find such big effects," Peter Rothwell, professor of neurology at the University of Oxford and co-author of the study, said in an interview. "I think it's certainly an important finding for prevention of cancer, both in terms of the effects of Aspirin itself and I think also in terms of the more general principle that cancers are preventable by simple compounds."
Aspirin, the brand name of the drug acetylsalicylic acid (ASA), is already known to prevent heart attacks or strokes in some people, particularly those who are at increased risk or have already suffered one, because it makes blood less likely to clot.
But in recent years, a growing collection of research suggests ASA may also inhibit cancer growth or incidence, perhaps by restricting enzymes that lead to inflammation.
In the new study, researchers analyzed data from eight previous trials comparing patients who had taken daily Aspirin to those who hadn't, and used death certificates and cancer registries to conduct a 20-year follow-up.
They found cancer deaths among patients on the daily ASA regimen were 20 per cent lower after five years than the control group (which did not take the medication), an effect that was still evident 20 years later. Aspirin seemed to have the biggest effect on gastrointestinal cancers, such as stomach or pancreatic cancer, reducing deaths by 35 per cent after 20 years.
Prostate cancer deaths were reduced by 10 per cent after the 20-year follow up, lung cancer deaths were reduced by 30 per cent and colorectal cancer deaths were cut by 40 per cent.
More than 12,600 patients were tracked as part of the 20-year follow-up; of those, 1,634 had died of cancer by the end of the tracking period. Patients took different doses of medication in the trials included in the study, but researchers concluded doses higher than 75 milligrams a day (the amount in low-dose Aspirin) had no greater benefits.
Dr. Rothwell said the findings provide solid evidence low-dose ASA can play an important role in cancer prevention.
Although he said it's too early to make a blanket endorsement for the general population, Dr. Rothwell said the study "begins to tip things in the direction of [Aspirin]being worth taking" for cancer prevention, particularly for those people who have a family history of gastrointestinal and other types of cancers they found were affected by the medication.
However, there is a note of caution for patients to consider: Fully understanding the relationship between Aspirin and cancer prevention, as well as the risks of bleeding, anemia and other side effects among patients who take it daily, is still a long way off.
"It's the kind of thing an individual should discuss with his or her physician before just jumping into it," said Carolyn Gotay, professor and Canadian Cancer Society Chair in cancer primary prevention in the School of Population and Public Health at the University of British Columbia.
Dr. Gotay also pointed out several weaknesses in the study that need to be addressed before health recommendations could be changed, such as the fact only a small proportion of women were included. The side effects of taking Aspirin over a long-term period, which can include gastrointestinal bleeding, must also be taken into account.
Yet, Dr. Gotay said the concept of using Aspirin to ward off cancer has "potential for widespread use" and may help ingrain the idea that there are real steps people can take to prevent the disease.
"I think if the idea is that people can think of cancer prevention as reality, think of ways they can reduce their risk, this would be one part of a whole package," she said.