Design of randomized controlled trials to estimate cancer-mortality reductions from multicancer detection screening

Large-scale MCD RCTs would have 89% power to detect an approximate 10% cancer mortality reduction over a relatively short 7-9 year timeframe from trial entry. The estimated NNS for MCD RCTs compares favorably with mammographic screening. Most prevented cancer deaths in a well-powered MCD RCT would likely be from lung cancer. Non-lung and non-colorectal cancer sites could be a meaningful proportion of prevented cancer deaths, but power is insufficient to isolate non-lung-cancer mortality reductions.