The anti-tumor benefits of aspirin are achieved with a trade-off of increased toxicities, as described in a meta-analysis of 22 randomized trials of aspirin for vascular disease prevention. Most notable are the risks of gastrointestinal toxicities, mainly ulcers and GI bleeding (RR=1.62; 95% CI, 1.25–2.09), or intracranial bleeding (RR=1.65; 95% CI, 1.06–5.99)