ERBB2 and cancer: After demonstrating that cfDNA and EV can be isolated from BrCa patients with no significant differences in the recovered amount across the two subtypes (Figure 2b and e) and that they allow the detection of cancer–associated alterations (Figure 3a,b), we sought to quantify the ability of such circulating nucleic acids to screen for the status of a critical BrCa biomarker, such as HER2 in early stage BrCa liquid biopsies.