{"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":["paper-mcneil-j-natl-cancer-inst"],"journals":[],"dependsOn":[],"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":"msi-high-colorectal","kind":"cancer","name":"Mismatch-repair deficient (MSI-high) colorectal cancer","route":"/cancers/msi-high-colorectal/"},{"id":"polycythaemia-vera","kind":"cancer","name":"Polycythaemia vera (PV)","route":"/cancers/polycythaemia-vera/"},{"id":"primary-myelofibrosis","kind":"cancer","name":"Primary myelofibrosis","route":"/cancers/primary-myelofibrosis/"}],"paper":[{"id":"paper-capp2-aspirin-lynch-lancet-2020","kind":"paper","name":"CAPP2: two years of aspirin cuts bowel cancer in Lynch syndrome by more than a third over 10 years","route":"/key-papers/paper-capp2-aspirin-lynch-lancet-2020/"},{"id":"paper-mcneil-j-natl-cancer-inst","kind":"paper","name":"Effect of Aspirin on Cancer Incidence and Mortality in Older Adults","route":"/key-papers/paper-mcneil-j-natl-cancer-inst/"}],"trial":[{"id":"nct05411718","kind":"trial","name":"A Phase IIa Randomized, Double-Blinded Clinical Trial of Naproxen or Aspirin for Cancer Immune Interception in Lynch Syndrome","route":"/trials/nct05411718/"},{"id":"nct02301286","kind":"trial","name":"A Trial of Aspirin on Recurrence and Survival in Colon Cancer Patients","route":"/trials/nct02301286/"},{"id":"add-aspirin","kind":"trial","name":"Add-Aspirin","route":"/trials/add-aspirin/"},{"id":"alascca","kind":"trial","name":"ALASCCA","route":"/trials/alascca/"},{"id":"nct03326791","kind":"trial","name":"Aspirin in Colorectal Cancer Liver Metastases","route":"/trials/nct03326791/"},{"id":"nct03464305","kind":"trial","name":"ASPIRIN Trial Belgium","route":"/trials/nct03464305/"},{"id":"aspree","kind":"trial","name":"ASPREE (ASPirin in Reducing Events in the Elderly)","route":"/trials/aspree/"},{"id":"nct03957902","kind":"trial","name":"Assessment of Direct Biomarkers of Aspirin Action to Develop a Precision Chemoprevention Therapy of Colorectal Cancer","route":"/trials/nct03957902/"},{"id":"capp2","kind":"trial","name":"CAPP2","route":"/trials/capp2/"},{"id":"nct07762703","kind":"trial","name":"Combination Immunotherapy Treatment for Locally Advanced Unresectable or Metastatic, PD-L1 Negative (CPS<10), gBRCA Negative, Triple Negative Breast Cancer Incl","route":"/trials/nct07762703/"},{"id":"nct00316927","kind":"trial","name":"Dexamethasone, Aspirin, and Diethylstilbestrol in Treating Patients With Locally Advanced or Metastatic Prostate Cancer","route":"/trials/nct00316927/"},{"id":"nct02497820","kind":"trial","name":"Finding the Best Dose of Aspirin to Prevent Lynch Syndrome Cancers","route":"/trials/nct02497820/"},{"id":"nct00055731","kind":"trial","name":"Hormone Therapy With or Without Docetaxel And Estramustine in Treating Patients With Prostate Cancer That is Locally Advanced or At High Risk of Relapse","route":"/trials/nct00055731/"},{"id":"nct05637567","kind":"trial","name":"Perioperative Platelet Inhibition With Acetylsalicylic Acid in Patients With Resectable Tumors of the Pancreatic Head","route":"/trials/nct05637567/"},{"id":"pt-1","kind":"trial","name":"PT-1 (Primary Thrombocythaemia 1)","route":"/trials/pt-1/"},{"id":"nct05462613","kind":"trial","name":"Regorafenib With Low-dose Chemotherapies and Aspirin Followed by Standard Chemotherapies in Metastatic Colorectal Cancer","route":"/trials/nct05462613/"}],"person":[{"id":"john-burn","kind":"person","name":"John Burn","route":"/people/john-burn/"}],"term":[{"id":"erythromelalgia","kind":"term","name":"Erythromelalgia","route":"/terms/erythromelalgia/"},{"id":"ipset-thrombosis","kind":"term","name":"IPSET-thrombosis score (essential thrombocythaemia)","route":"/terms/ipset-thrombosis/"},{"id":"microenvironment-inflammation-theory","kind":"term","name":"Microenvironment and inflammation: tumours as wounds that do not heal","route":"/terms/microenvironment-inflammation-theory/"}]}}