By comparing biopsy and plasma samples over 3 years from a patient diagnosed with metastatic breast cancer, researchers discovered that circulating tumor DNA can be useful for tracking cancer spread and response to treatment (Murtaza M et al. Nat Commun. 2015;6:8760).
Using exome and targeted amplicon sequencing techniques, a team led by investigators at the University of Cambridge in the United Kingdom performed genetic analyses of 8 tumor biopsies and 9 plasma samples collected over 1193 days from the patient, who had metastatic estrogen receptor–positive and human epidermal growth factor receptor 2–positive disease and was receiving 2 lines of targeted therapy.
Hampton T. Circulating Tumor DNA Helps Track Cancer. JAMA. 2016;315(1):19. doi:10.1001/jama.2015.17482