Full-Strength Aspirin Over Time Has Ambiguous Effect on Cancer Risk

ATLANTA, April 10 -- Five years or more of daily adult-strength aspirin is associated with modest protection against colorectal, prostate, and breast cancers, investigators here reported.
However, daily low-dose aspirin (81 mg) used for cardiovascular protection is not associated with any additional protection against cancer, in keeping with other studies, reported Eric J. Jacobs, Ph.D., of the American Cancer Society, and colleagues, in the April 18 issue of the Journal of the National Cancer Institute.
The five-year findings emerged from a huge observational survey. But the investigators cautioned that a decade or longer will be needed to determine whether the association they found matters. At the moment, they wrote, "our results do not have immediate clinical implications."
In an accompanying editorial, María Elena Martínez, M.P.H., Ph.D., of the University of Arizona in Tucson, and E. Robert Greenberg, M.D., of Dartmouth Medical College in Hanover, N.H., pointed out that chronic use of full-strength aspirin (325 mg) may also have GI and hematologic consequences that obviate any potential anticancer benefit that may emerge in a long-term trial.
"Although such a trial merits careful consideration, it might be difficult to conduct it among average-risk individuals, given the toxicity of aspirin at doses greater than 80 mg/day," they wrote. "Thus, the authors appear justified in concluding that their results do not have immediate clinical implications, but they clearly illustrate the potential future importance of aspirin and other anti-inflammatory interventions as cancer control strategies."