Aspirin and cancer risk: A meta-analysis to 2011


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Carlo La Vecchia
Istituto di Ricerche Farmacologiche Mario Negri & University of Milano, Milan, Italy

Abstract

Aspirin has been associated to a reduced risk of colorectal and possibly of a few other common cancers, but quantification remains open to discussion. To provide an up-to-date quantification of this association, we conducted a meta-analysis of all observational studies on aspirin and 12 selected cancer sites published up to September 2011 including a total of 139 studies (Bosetti et al., 2012). Regular aspirin is associated with a statistically significant reduced risk of colorectal cancer [summary relative risk (RR) from random effects models board on over 30,000 cases = 0.73, 95% confidence interval (CI) 0.67-0.79], and of other digestive tract cancers (RR = 0.61, 95% CI = 0.50-0.76, for squamous cell esophageal cancer; RR = 0.64, 95% CI = 0.52-0.78, for esophageal and gastric cardia adenocarcinoma; and RR = 0.67, 95% CI = 0.54-0.83, for gastric cancer), with somewhat stronger reductions in risk in case-control than in cohort studies. Modest inverse associations were also observed for breast (RR = 0.90, 95% CI = 0.85-0.95) and prostate cancer (RR = 0.90, 95% CI = 0.85-0.96), while lung cancer was significantly reduced in case-control studies (0.73, 95% CI = 0.55-0.98) but not in cohort ones (RR = 0.98, 95% CI = 0.92-1.05). No meaningful overall associations were observed for cancers of the pancreas, endometrium, ovary, bladder, and kidney. Thus, a large number of observational studies indicate a beneficial role of aspirin on colorectal and other digestive tract cancers; modest risk reductions were also observed for breast and prostate cancer. Results are, however, heterogeneous across studies and dose-risk and duration-risk relationships are still unclear for several of the associations.

Bosetti C, Rosato V, Gallus S, Cuzick J, La Vecchia C. Aspirin and cancer risk: a quantitative review to 2011. Ann Oncol 2012;23:1403-15