Blood-Based Multi-Cancer Early Detection Tests (MCEDs) as a Potential Approach to Address Current Gaps in Cancer Screening

Screening and early detection is one of the most effective approaches to reduce the population-level impact of cancer. Novel approaches to screening such as multi-cancer early detection tests (MCEDs) may further reduce cancer incidence and mortality. Many MCEDs detect fragments of circulating DNA containing mutations that originated from tumour cells, thereby informing both the presence of cancer and the cell-type of origin. In this review, we examine the current evidence of MCEDs as a potential tool to improve population-based cancer outcomes. We review the role of MCEDs to address low participation rates, disparities among underserved populations, changing epidemiology of common cancers, and the absence of screening tests for many cancer types. MCEDs have the potential to increase participation in cancer screening programs, as they may be less invasive than other procedures, and can screen for multiple cancer types in one appointment. Additionally, due to the lack of specialized collection equipment needed for these tests, underscreened populations and targeted populations could gain greater access to screening. Finally, because MCEDs can detect cancer types without screening tests that are moderately common and increasing in western populations, efficacious tests for these sites could alleviate the cancer burden and improve patient outcomes. While these tests offer great promise, considerable limitations and evidence gaps must be addressed. Notable limitations include scenarios where early detection does not improve survival outcomes, the costs and impact on health care resources for false positives, and false reassurance with subsequent lack of adherence to existing screening protocols.