"News about the cancer potential of aspirin use has been really encouraging lately," said Dr. Michael Thun of the American Cancer Society, who worked on the study. "Things are moving forward, but it is still a work in progress."
Medical guidelines in the US already urge people to take low doses of aspirin to prevent heart disease if the predicted benefits outweigh the risk of side effects, or if they have already suffered a heart attack.
Whether those recommendations should be broadened to include cancer prevention is still up in the air, however.
Earlier this year, an analysis of previous clinical trials showed that people on aspirin were less likely to die of cancer than those not on the medication, with a 37-per cent drop in cancer deaths observed from five years onwards.
The new report, published Friday in the Journal of the National Cancer Institute, is based on real-life observations instead of experiments. It includes a decade's worth of data from more than 100,000 men and women in the US, most over 60 and all of them non-smokers.
People who said they took daily aspirin - whether 'baby' or adult strength - had a 16-per cent lower risk of dying from cancer than non-users overall, Thun and his colleagues found.
For men, the difference came out to 103 fewer cancer deaths a year per 100,000 people; for women, the number was 42.
The effect was strongest for gastrointestinal cancers, such as colon cancer and stomach cancer. But it didn't seem to matter whether people had been on aspirin for more or less than five years.
Because the study wasn't a clinical trial, it's hard to know if the findings can be chalked up to aspirin or if something else is at play.
Still, Thun said the results would favor broadening the aspirin guidelines to include cancer prevention based on an individual risk-benefit assessment. But he added that it will take scientists a few years to mull over all of the existing evidence.