Long-term follow-up of CAPP2: aspirin prevents colorectal cancer in Lynch syndrome carriers

Reference

Burn J, Sheth H, Elliott F, et al, for the CAPP2 Investigators. 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(10240):1855-1863.

Synopsis

We previously reported data from the CAPP2 study in which patients who were carriers of hereditary nonpolyposis colorectal cancer (Lynch syndrome) were randomized to receive 600 mg aspirin daily (n = 427) or placebo (n = 434) for 2 years with an option to continue for an additional 2 years. At the time of the initial report, there was no significant reduction in cancers in the intention-to-treat analysis, but there was a significant reduction in cancers using a per-protocol analysis. This paper reports the outcomes of a longer term follow-up of this study. The authors used national cancer registries to provide data for up to 20 years after randomization. This resulted in an average follow-up duration of 10 years during which time 40 (9.4%) of the aspirin-treated participants developed colorectal cancer compared with 58 (13.4%) of the control patients (number needed to treat = 25). Although other cancers are also associated with Lynch syndrome (eg, endometrial, ovarian, and pancreatic), aspirin did not reduce these other cancers and it didn't reduce non-Lynch syndrome cancers. The authors don't report on the harms of aspirin during the treatment period.