The uses and applications of circulating tumor (ct)DNA measurements are explored here by Pierre-Jean Lamy, PharmD, PhD, of the Medical Institute of Genomic Analysis, Montpellier, France. Speaking at the 2018 National Cancer Research Institute (NCRI) Cancer Conference, held in Glasgow, UK, Dr Lamy provides an overview of the potential uses of ctDNA measurement in cancer diagnosis and management, including the benefits, notably the detection of RET mutations in patients with non-small cell lung cancer (NSCLC), and the future of its implementation.