Aspirin and the risk of nondigestive tract cancers: An updated meta-analysis to 2019

Aspirin has been associated with a reduced risk of colorectal and other selected digestive tract cancers, but the evidence for other neoplasms is still controversial. To provide an up-to-date quantification of the role of aspirin on lung, breast, endometrium, ovary, prostate, bladder, and kidney cancer, we conducted a systematic review and meta-analysis of all observational studies published up to March 2019. We estimated pooled relative risk (RR) of cancer or cancer death for regular aspirin use vs non-use by using random-effects models, and, whenever possible, we investigated dose- and duration-risk relations. A total of 148 studies were considered. Regular aspirin use was associated to a reduced risk of lung (RR = 0.88, 95% confidence interval [CI] = 0.79-0.98), breast (RR = 0.90, 95% CI = 0.85-0.95), endometrial (RR = 0.91, 95% CI = 0.84-0.98), ovarian (RR = 0.91, 95% CI = 0.85-0.97) and prostate (RR = 0.93, 95% CI = 0.89-0.96) cancer. However, for most neoplasms, nonsignificant risk reductions were reported in cohort and nested case-control studies and there was between-study heterogeneity. No association was reported for bladder and kidney cancer. No duration-risk relations were observed for most neoplasms, except for an inverse duration-risk relation for prostate cancer. The present meta-analysis confirms the absence of appreciable effect of regular aspirin use on cancers of the bladder and kidney and quantifies small and heterogeneous inverse associations for other cancers considered.

Automated summary

The study suggests that regular aspirin use is associated with a reduced risk of lung, breast, endometrial, ovarian, and prostate cancer, while no significant association was found for bladder and kidney cancer. The duration-use relations varied among different types of cancer, with an inverse relation observed for prostate cancer. The overall meta-analysis confirms the modest protective effect of regular aspirin use on certain cancers.