Can Aspirin Help Keep Cancer At Bay?

Among 22,507 cancer-free postmenopausal women who participated in the Iowa Women's Health Study and provided information on aspirin and NSAID use, those who said they regularly used aspirin had a 16 percent reduced risk of developing cancer more than a decade later, as well as a 13 percent reduced risk of dying from cancer over this same time period, compared to women who did not use aspirin. But there was no statistically significant impact on cancer incidence or mortality among women who used non-aspirin NSAIDs, compared to those who did not, say researchers from the Mayo Clinic, in Rochester, Minnesota.

The researchers also looked at whether smoking status had any impact on the potential preventive effects of aspirin and found that while these agents were associated with lower cancer incidence and mortality among former and never smokers, the same apparent benefits were not seen among active smokers.

These study results do not mean, however, that women should throw away their NSAIDs or pick up a bottle of aspirin, says the study's lead author, Aditya Bardia, M.D., M.P.H. "This is just one study," he says. "However, it does provide provocative evidence that regular aspirin use may play a role in preventing the most common chronic diseases in western countries, namely cancer and heart disease."

The different impact of aspirin compared to other NSAIDs was somewhat surprising, the researchers say. "While chemically different, these agents share at least one similar mechanism of action so you might have expected them to have comparable effects," says Jon Ebbert, M.D., the senior author on the study.

Specifically, aspirin and other NSAIDs reduce inflammation through inhibition of cyclooxygenase (COX) enzymes. These enzymes are responsible for the formation of prostaglandins, which can drive inflammation and possibly stimulate cancer development in a number of organ sites, Dr. Ebbert said.

Previous studies have evaluated whether aspirin or other NSAIDs prevent specific cancers, such as breast cancer. "But this study is unique because we were able to evaluate comprehensive endpoints such as total cancer incidence and cancer mortality, which are more clinically relevant outcomes for patients," Dr. Bardia said.

While the researchers note that one of the weaknesses of this study was that the women were given only a single survey of aspirin and non-aspirin NSAID use, it also had many strengths including the prospective cohort study design, relatively long follow-up (up to 12 years) on a large number of participants, during which time many developed (3,487) and died (1,193) from cancer. The authors were also able to adjust the results for a large number of lifestyle factors, and found little evidence that these other factors could explain the aspirin and cancer associations observed in this study.