Long-term follow-up of the CAPP2 study demonstrates the benefits of daily aspirin for preventing hereditary colorectal cancer (Lynch syndrome)
CAPP2 is an international, double-blind, randomised, placebo-controlled registry-based study of cancer prevention in people with Lynch syndrome. Lynch syndrome is a hereditary genetic condition which increases the person’s risk of developing certain cancers. The 10 year follow up of CAPP2 gives a long-term assessment of the effect of daily aspirin for cancer prevention in a higher risk population. The study follows 861 patients (mean age 45 years) randomly allocated to receive aspirin 600 mg daily or placebo and monitors cancer outcomes for 10-20 years. The primary outcome measure was colorectal cancer.
In the group receiving aspirin 40 out of the 427 people (9%) developed colorectal cancer in comparison with the 58 (13%) of the 434 taking placebo. An intention-to-treat Cox proportional hazards analysis demonstrated the protective effect of aspirin against colorectal cancer (HR 0.65 [95% CI 0.43-0.97]; p=0.035). The number needed to treat was 24.
Non-colorectal Lynch syndrome cancers were found to be the same in each group. It is interesting that in this relatively young cohort no difference in significant adverse events was observed between the two groups and no significant difference in compliance was noted.
The colorectal cancer protective effect of aspirin in the CAPP2 study took about 5 years to be seen and lasted throughout the observed period, up to 20 years for some participants.
This adds to evidence from over 100 observation studies, carried out since Kune and colleagues first reported a protective effect of aspirin in colorectal cancer, demonstrating aspirin’s cancer prevention benefits.
The authors state:
‘There is now a strong case for prescribing aspirin to young adult carriers of a germline DNA mismatch repair gene defect.’
The CaPP3 study is currently ongoing having closed to recruitment in March 2019 and it is hoped that it will inform the best dose of aspirin to use to achieve cancer prevention whilst minimising adverse events.
For further information please see:
Burn J, Sheth H, Elliott F et al. Cancer prevention with aspirin in hereditary colorectal cancer (Lynch syndrome), 10-year follow-up and registry-based 20-year data in the CAPP2 study: a double-blind, randomised, placebo-controlled trial. Lancet 2020; 395:1855-63.
