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

Background: Determining whether screening with multicancer detection (MCD) tests saves lives requires randomized controlled trials (RCTs). To inform RCT design, we estimated cancer-mortality outcomes from hypothetical MCD RCTs.

Methods: We used the Hu-Zelen model, previously used to plan the NLST, to estimate mortality reductions, sample-size, and power for 9 cancers for different RCT design parameters and MCD test parameters.

Results: Our base-case RCT with 5 yearly screens and 100,000 people ages 60-74 in each arm, who also undergo standard-of-care screens, has 87-89% power to detect an 9-10% mortality reduction (NNS = 578-724) over 7-9 years. The majority of prevented deaths were from lung-cancers (base-case (64-66%) and all sensitivity analyses), 8-10% from colorectal-cancer, and 26% from the other 7-cancers, mostly from stomach/ovary/esophagus (due to excellent stage-1 survival) and less from liver/pancreas (poor stage-1 survival) or head/neck-cancer/lymphoma (excellent stage-4 survival). There was limited power for mortality reductions at most individual cancer sites. Base-case findings were sensitive to test sensitivity, stage-shifts, and mean sojourn times in the preclinical state (especially for lung-cancer), but 90% power could be recovered by recruiting a substantially higher risk population.

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