Cancer Blood Tests: Are they ready for primetime? Part 1

About this episode

Can a single tube of blood really detect dozens of cancers before symptoms appear? We dive into the science behind Galleri, a blood test that claims to detect more than 50 types of cancer from a simple blood draw. Recent headlines about the test ranged from “breakthrough” to “bust” after the release of results from a massive randomized clinical trial. In this Part 1 episode, we explore cell-free DNA, DNA methylation, machine learning, sensitivity, specificity, and positive predictive value. Along the way, we revisit the prenatal screening revolution, ask why detecting cancer earlier doesn’t always help patients, and learn how escaped DNA convicts end up swimming in a giant molecular pool party. And for the first time ever, Normal Curves ends on a cliffhanger: we’ll save the controversial results of that landmark trial for Part 2. Statistical topics • cancer screening • case-control studies • counterfactuals • machine learning • negative predictive value • overdiagnosis • positive predictive value • randomized clinical trials • screening tests • sensitivity and specificity • validation References • Bianchi DW, Chudova D, Sehnert AJ, et al. Noninvasive prenatal testing and incid