# Cancer prevention with aspirin in hereditary colorectal cancer (Lynch syndrome), 10-year follow-up and registry-based 20-year data in the CAPP2 study

Source: https://onco.cc/key-papers/paper-burn-capp2-aspirin-lynch-syndrome-lancet-2020/  
OnCo record `paper-burn-capp2-aspirin-lynch-syndrome-lancet-2020` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Two years of high-dose aspirin cut bowel cancers in people with Lynch syndrome by about a third over the following decade. It is the only drug shown in a randomised trial to prevent this cancer.

## Summary

In the double-blind CAPP2 trial, Burn, Sheth, Elliott and colleagues randomised 861 people with Lynch syndrome from 43 international centres to 600 mg of aspirin daily or placebo; 937 eligible participants of mean age 45 commenced treatment. Cancer outcomes were monitored for at least ten years from recruitment, with English, Finnish and Welsh participants followed for up to 20 years through registries. The primary endpoint was development of colorectal cancer, analysed by intention to treat and per protocol.

Participants were followed for a mean of ten years, approximating 8,500 person-years. Adverse events during the intervention phase were similar between groups.

## Fields

- Kind: Key paper
- Last checked: 2026-09-24
- Tags: colorectal-evidence
- Journal: The Lancet
- Year: 2020
- DOI: 10.1016/S0140-6736(20)30366-4
- Authors: Burn J, Sheth H, Elliott F, et al.
- Findings: 40 of 427 participants on aspirin developed colorectal cancer against 58 of 434 on placebo.; Intention to treat hazard ratio 0.65 (95 percent CI 0.43 to 0.97, p=0.035); incidence rate ratio 0.58 (0.39 to 0.87, p=0.0085).; Per protocol, in the 509 who completed two years: hazard ratio 0.56 (0.34 to 0.91, p=0.019) and incidence rate ratio 0.50 (0.31 to 0.82, p=0.0057).; Non-colorectal Lynch syndrome cancers occurred in 36 participants in each group, with no effect.
- What it means: Chemoprevention in a defined high-risk group is possible, and aspirin is now offered to Lynch syndrome carriers in UK practice; the CaPP3 dose-finding study asks whether a much smaller dose does the same.
- Caveats: 600 mg daily is a high dose with bleeding risk; CaPP3 was designed to find the lowest effective dose.; Intention-to-treat significance is marginal, and the effect on non-colorectal Lynch cancers was absent.; Applies to Lynch syndrome carriers, not to the general population.

## Sources

- Lancet 2020: https://doi.org/10.1016/S0140-6736(20)30366-4
- PubMed: https://pubmed.ncbi.nlm.nih.gov/32534647/
- Europe PMC full text (PMC7294238): https://europepmc.org/article/MED/32534647

## Connected records

- key papers: [Colonoscopic polypectomy and long-term prevention of colorectal-cancer deaths (National Polyp Study)](https://onco.cc/key-papers/paper-zauber-national-polyp-study-colonoscopic-polypectomy-nejm-2012/), [Comprehensive molecular characterization of human colon and rectal cancer](https://onco.cc/key-papers/paper-tcga-colon-rectal-molecular-characterization-nature-2012/)
- cancers: [Colon cancer (adenocarcinoma of the colon)](https://onco.cc/cancers/colon-cancer/), [Colorectal cancer](https://onco.cc/cancers/colorectal/)
- fronts: [Prevention & Risk](https://onco.cc/fronts/prevention/)
- technologies: [Germline (hereditary) testing](https://onco.cc/technologies/germline-testing/)
- drugs: [Aspirin](https://onco.cc/drugs/aspirin/)
- terms: [Lynch syndrome](https://onco.cc/terms/lynch-syndrome/)
- targets: [Mismatch repair proteins (MLH1, MSH2, MSH6, PMS2)](https://onco.cc/targets/mmr/)
- bottlenecks: [Inherited risk is mostly unidentified](https://onco.cc/bottlenecks/b-hereditary-risk/), [No incentive to repurpose cheap drugs](https://onco.cc/bottlenecks/b-generic-repurposing/), [Prevention we already have is not deployed](https://onco.cc/bottlenecks/b-prevention-adoption/)
- journals: [The Lancet](https://onco.cc/journals/lancet/)

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