Michail Ignatiadis, MD, PhD, Institut Jules Bordet and Université Libre de Bruxelles, Brussels, Belgium, discusses the results of a single-center study evaluating the utility of a personalized circulating tumor DNA (ctDNA) assay. The detection of ctDNA post neoadjuvant chemotherapy is associated with disease relapse in early breast cancer supporting interventional trials in this setting. This interview took place at the San Antonio Breast Cancer Symposium 2021 in San Antonio.