Taking aspirin regularly may help ward off cancers of the gastrointestinal (GI) tract, suggested the largest study of its kind to date—a meta-analysis of 113 studies, published in the Annals of Oncology in May 2020.
For colorectal cancer, the third most frequent cancer killer of Americans, aspirin was associated with a 27 percent reduced risk overall—10 to 13 percent for low-dose aspirin (75 to 100 milligrams) and 36 percent for regular-dose aspirin (325 milligrams). Protection was greater for people taking aspirin at least 10 years as opposed to less than three years.
This follows earlier research that similarly linked aspirin to reduced risk of colon cancer, a benefit acknowledged by the U.S. Preventive Services Task Force in 2016, though the group stopped short of recommending aspirin specifically for that purpose, and though not all previous studies have found this.
For other GI cancers, risk reductions were 22 percent for pancreatic cancer, 33 percent for esophageal cancer, 36 percent for stomach cancer, and 38 percent for liver cancer.
According to Steven Jacobsohn, MD, a gastroenterologist and member of our editorial board, “the results are promising, though they don’t, at least yet, justify expanding the current aspirin guidelines for heart protection to include the drug’s use for prevention of GI cancers,” since aspirin can cause bleeding in the GI tract and increase the risk of hemorrhagic stroke. Joint guidelines from the American Heart Association and the American College of Cardiology, updated in 2019, recommend that select people ages 40 to 70 take low-dose aspirin only if they are at increased risk for cardiovascular disease and not at increased risk for bleeding—and they recommend against routine aspirin use in people over 70 because the heart benefits do not outweigh the bleeding risk.
More caveats about the meta-analysis: Besides that it was funded by the aspirin maker Bayer, it looked only at observational studies, which didn’t prove cause and effect. Independent randomized controlled trials are needed to confirm any benefits that aspirin might have on GI cancers.
Bottom line: The latest findings are not robust enough to recommend aspirin for GI-cancer protection across the board. But if you have a first-degree relative with colon cancer or have had a polyp removed that had a higher potential of becoming malignant, you might talk with your doctor about taking aspirin and the recommended dose. And if you already take aspirin for heart protection (always under your doctor’s guidance), you may, as a fortuitous perk, be getting some cancer protection as well.
This article first appeared in the UC Berkeley Wellness Letter.