Taking aspirin once a day reduces a person’s risk of dying from cancer, but the benefit may not be as great as was previously thought, a new study says.

In the study, people who took a daily aspirin were 8 to 16 percent less likely to die over an 11-year period compared with people who did not take aspirin.

That’s much less than the 37 percent reduced risk of cancer-related death found by a study published in March in the journal the Lancet.

“Our results provide additional support for a potential benefit of daily aspirin use for cancer mortality, but important questions remain about the size of this potential benefit,” said Eric Jacobs, of the American Cancer Society’s Epidemiology Research Program, who conducted the new study.

Although the results are encouraging, “it is still premature to recommend people start taking aspirin specifically to prevent cancer,” Jacobs said. “Expert committees that develop clinical guidelines will consider the totality of evidence about aspirin’s risks and benefits when guidelines for aspirin use are next updated,” he said.

The benefit of aspirin seen in the Lancet study seemed larger than expected, given that previous work found no decrease in the risk of dying from cancer among people who took aspirin every other day, Jacobs said.

In the new study, Jacobs and colleagues analyzed information from more than 100,000 people who were periodically asked about their use of aspirin.

Between 1997 and 2008, about 5,100 participants died of cancer.

The yearly rate of death from cancer among men who did not take aspirin was 596 deaths per 100,000 people. The rate was 493 deaths per 100,000 people among men who took daily aspirin.

For women, the yearly rates of death were 337 deaths per 100,000 among those who did not take aspirin, and 295 deaths per 100,000 among those who took daily aspirin.

Daily aspirin was associated with a reduced risk of cancer-related death regardless of how many years participants took the drug. This finding was in contrast to previous studies, some of which have shown people need to take aspirin daily for 10 or more years to have a lower risk of dying from cancer.

There was no link between aspirin use and risk of cancer-related death for smokers, the researchers said.

The new findings on aspirin and risk of cancer-related death echo those of studies conducted in the past, Dr. John Baron, of the University of North Carolina School of Medicine, wrote in an editorial accompanying the study.

“The big picture on aspirin use and cancer is very positive,” Baron said.

However, taking aspirin does come with risks, Baron said, including an increased risk of gastrointestinal bleeding.

Because people in the new study were not randomly assigned to take daily aspirin, the findings may have been influenced by the health behaviors of the study population, the researchers noted. For example, those who took a daily aspirin may have been more likely to seek medical attention, they said.

The study and editorial are published in today’s (Aug. 10) issue of the Journal of the National Cancer Institute.

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