In a study of 25,570 people in the British journal "Lancet", the number of deaths from cancer was lowered by 21 percent in those who took low dose aspirin for at least five years.
"We were surprised by the extent to which it does reduce the death rate," said Professor Tom Meade of the London School of Hygiene and Tropical Medicine, the study's author.
The numbers over the long term were even more striking: The risk of death after 20 years was reduced by about 10 percent for prostate cancer, 30 percent for lung cancer, 40 percent for colorectal cancer and 60 percent for esophageal cancer.
Which raises the question: Should everyone take low dose aspirin?
Today the American Cancer Society said no; and that quote: "It would be premature to recommend people start taking aspirin specifically to prevent cancer."
That's because low dose aspirin can lead to dangerous internal bleeding.
There are risks and there could be side effects.
So in general, people who should not take aspirin are those who have an allergy to aspirin, are prone to bleeding, already on blood thinners or have liver or stomach problems. They should talk to their doctor.
Still, evidence that it might help fight cancer is intriguing for doctors.
"It's consistent with the hypothesis that an anti-inflammatory agent can prevent cancer," said Dr. Cliff Hudis of Memorial Sloan-Kettering Cancer Center. "It's not the only evidence, but it's the largest body of evidence so far."
Since this study didn't show why aspirin reduced deaths from so many types of cancer, more research still needs to be done.