{"entity":{"id":"aspirin","kind":"drug","name":"Aspirin","aka":["Acetylsalicylic acid","Low-dose aspirin"],"tldr":"Aspirin is not a cancer drug but sits in cancer care in two places: low doses prevent clots in polycythaemia vera and essential thrombocythaemia, and long-term use lowers colorectal cancer in people with Lynch syndrome, while a trial in the healthy elderly found no benefit and possible harm.","summary":"In the myeloproliferative neoplasms, low-dose aspirin is given to almost everyone with polycythaemia vera and to low-risk and high-risk essential thrombocythaemia, because activated platelets cause both the microvascular symptoms (erythromelalgia, headache) and the arterial clots that drive mortality; the ECLAP trial in polycythaemia vera showed fewer combined cardiovascular events with aspirin. In prevention, the CAPP2 trial in Lynch syndrome found that 600 mg of aspirin a day for at least two years roughly halved colorectal cancers over the following decade, and long-term follow-up of cardiovascular trials suggested fewer colorectal cancer deaths. Against that, ASPREE, a trial in healthy adults over 70, found more cancer deaths on aspirin than placebo, so aspirin is not recommended for cancer prevention in older people without a specific indication. The Add-Aspirin trial is testing aspirin after treatment for breast, colorectal, gastro-oesophageal and prostate cancer. Its harms are bleeding, especially in the gut, and it must be avoided in essential thrombocythaemia with acquired von Willebrand deficiency.","status":"established","asOf":"2026-09-16","links":[{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/Aspirin"},{"label":"CAPP2 long-term follow-up, Lancet 2020","url":"https://doi.org/10.1016/S0140-6736(20)30366-4"},{"label":"ASPREE cancer outcomes, JNCI 2021","url":"https://doi.org/10.1093/jnci/djaa114"},{"label":"Add-Aspirin trial","url":"https://www.addaspirintrial.org/"}],"tags":["mpn","prevention"],"related":[],"cancers":["polycythaemia-vera","essential-thrombocythaemia","colorectal"],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"notes":[],"modality":"Antiplatelet and anti-inflammatory small molecule (cyclo-oxygenase inhibitor), used in cancer for thrombosis prevention and studied for chemoprevention","mechanism":"Irreversibly blocks cyclo-oxygenase 1 in platelets, stopping thromboxane production and platelet clumping; at higher doses also blocks cyclo-oxygenase 2 and prostaglandin-driven inflammation, the proposed route to its effect on colorectal cancer.","approvals":[],"mechanismSteps":[],"toxicity":[],"access":[],"regulatoryEvents":[]},"route":"/drugs/aspirin/","neighbours":{"cancer":[{"id":"colorectal","kind":"cancer","name":"Colorectal cancer","route":"/cancers/colorectal/"},{"id":"essential-thrombocythaemia","kind":"cancer","name":"Essential thrombocythaemia (ET)","route":"/cancers/essential-thrombocythaemia/"},{"id":"polycythaemia-vera","kind":"cancer","name":"Polycythaemia vera (PV)","route":"/cancers/polycythaemia-vera/"}],"term":[{"id":"erythromelalgia","kind":"term","name":"Erythromelalgia","route":"/terms/erythromelalgia/"}]}}