This research study is studying a drug intervention as a possible chemoprevention strategy for colorectal cancer.

The name of the study intervention involved in this study is:

• Low Dose Aspirin

This is prospective, double-blind, placebo-controlled, randomized clinical trial to measure the effects of daily low-dose (81 mg/day) aspirin on tissue, urine, plasma, and stool biomarkers associated with colorectal cancer with a focus on the effect of age. It is a direct extension of an earlier study: ASPIRED trial NCT02394769

Aspirin is part of the non-steroidal anti-inflammatory drug (NSAID) family, which are drugs routinely used for their pain-killing (analgesic), fever-reducing (antipyretic), or anti-inflammatory properties. Most NSAIDs are available as over-the-counter formulations. Substantial evidence has conclusively demonstrated that aspirin reduces the risk of colorectal polyps and cancer, yet there remains uncertainty surrounding its mode of action. Aspirin may prevent colorectal cancer through multiple interrelated biological mechanisms including the reduction of chronic inflammation, a known risk factor for colorectal cancer. Aspirin has been shown to directly affect prostaglandins, a class of biologic molecules that play important roles in controlling the normal inflammatory responses within your body. The exact mechanism by which aspirin acts to prevent colorectal cancer is still unknown.This study is looking at the mechanisms of aspirin's anti-cancer effect, which may lead to the discovery of novel specific characteristics (markers) that can be used to select patients for aspirin treatment. the study will also look at the effect age may have on these mechanisms.

The research study procedures include screening for eligibility and study treatment and scheduling two clinical research visits immediately before and after intervention with the study drug.

Participants will be randomized into two groups.

• Arm A: Daily Placebo (no aspirin) for the duration of the study.
• Arm B: Daily low dose aspirin (81 mg/day) for the duration of the study.

Participants may be contacted periodically after the study (no more than 1- 2 times annually) for up to 10 years to follow-up on additional information including any continued aspirin use or follow-up colonoscopy results.

It is expected that about 160 people will take part in this research study.

The National Cancer Institute (NCI) of the National Institutes of Health (NIH) is supporting this research study by providing funding for the research study.

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 cancer (including esophageal, small intestine, colon, pancreatic), or any diagnosis of other cancers (with the exception of non-melanoma skin) in which there has been any active treatment within the last three years.
• Participants who are receiving any other investigational agents.
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to aspirin.
• Known diagnosis of Familial Adenomatous Polyposis (FAP) or Hereditary Non-Polyposis Colorectal Cancer (HNPCC, Lynch Syndrome).
• Any adenoma that was not completely removed during previous colonoscopy.
• History of aspirin intolerance, bleeding diathesis, peptic ulcer or gastrointestinal bleed, endoscopic complications, or contraindication to colonoscopy.
• Inability or unwillingness to abstain from non-protocol use of aspirin or NSAIDs or to provide blood, urine, or stool samples or colon biopsies during the study.
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements
• Pregnant or breastfeeding. Pregnant women are excluded from this study because aspirin is an FDA Category D agent with the potential for teratogenic or abortifacient effects. Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with aspirin, breastfeeding should be discontinued if the mother is treated with aspirin.
• Participant must be able to swallow pills.
• Participant is taking any anticoagulant agent (e.g. warfarin) or antiplatelet agent (e.g. clopidogrel).

The Dana-Farber / Harvard Cancer Center encourages and supports the responsible and ethical sharing of data from clinical trials. De-identified participant data from the final research dataset used in the published manuscript may only be shared under the terms of a Data Use Agreement. Requests may be directed to: [contact information for Sponsor Investigator or designee]. The protocol and statistical analysis plan will be made available on Clinicaltrials.gov only as required by federal regulation or as a condition of awards and agreements supporting the research.

Data can be shared no earlier than 1 year following the date of publication

Contact the Partners Innovations team at http://www.partners.org/innovation

3 months

Double-Blinded