ASPIRED-XT: ASPirin Intervention for the REDuction of Colorectal Cancer Risk -EXTension

Inclusion Criteria: * Participants must have undergone screening or surveillance colonoscopy with removal of at least one adenoma within the last 9 months. * Age greater than or equal to 18 years and less than 55 years or greater than or equal to 65 years at the time of enrollment This study will only include adult participants because colorectal carcinogenesis in children is more likely to be related to a cancer predisposition syndrome with distinct biological mechanisms compared with sporadic colorectal cancer in adults. * ECOG performance status ≤2 (Karnofsky ≥60%, see Appendix A). * Not currently taking aspirin (any dose) within the last 6 months. * The effects of aspirin on the developing human fetus are unknown. For this reason, women of child-bearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while she is participating in this study, she should inform her treating physician immediately. * Ability to understand and the willingness to sign a written informed consent document. Exclusion Criteria: * Use of any non-aspirin non-steroidal anti-inflammatory drug (NSAID) at any dose at least three times a week during the two months prior to randomization. * Diagnosis of inflammatory bowel disease, liver or kidney disease, bleeding diathesis. * Any prior diagnosis of gastrointestinal cance…