The largest and longest study of long-term, regular aspirin use finds that the drug may lead to a modestly reduced risk for some types of gastrointestinal cancers.
Regularly taking aspirin for years may protect users from some types of gastrointestinal (GI) cancers, especially colorectal cancer, according to Harvard researchers who presented their work at the annual American Association for Cancer Research (AACR) meeting held in Philadelphia last month. But long-term aspirin use may also come with an elevated risk of adverse effects, such as GI bleeding, cautioned Yin Cao, a research fellow at the Harvard School of Public Health who co-authored the study. “You need to consider the risk of (prolonged aspirin use),” Cao told The Scientist during an AACR poster session where she presented the work.
Previous studies of aspirin and cancer have been limited in terms of their size, length of follow-up, or ability to examine aspirin use in the context of other lifestyle factors. “Our research provides critical information regarding the full constellation of potential benefits of aspirin use, at a range of doses, timing, and duration of use, within a large population of individuals.”
Cao and her colleagues considered data collected from more than 100,000 men and women who had enrolled in separate studies in the 1980s. The researchers found an overall 5 percent decreased risk for all cancers in people who reported taking two or more aspirin tablets per week. This decrease was driven mostly by a 20% reduction in risk for GI cancers (including a 25% drop in colorectal cancer risk). There were no reductions in risk for breast, advanced prostate, lung, or other non-GI cancers associated with aspirin use, Cao added.
The Harvard study followed people for up to 32 years, longer than other studies. Cao and her colleagues showed that significant risk reductions for developing cancer came only after 16 years of using the drug, and the effects dissipated four years after discontinuing aspirin use. “Dose and duration both help,” she said.
Her team included Andrew Chan of Harvard Medical School.
