ddPCR data showed that 57% of the HER2‐ BrCa patients (Figure 4a, blue dots) group with the HDs, while 83% of HER2+ BrCa patients (Figure 4a, red dots) show higher signals than HDs on ERBB2 on EV‐RNA (ERBB2/EEF2; Figure 4a, y‐axis) and cfDNA (ERBB2/EIF2C1; Figure 4a, x‐axis). The gene discussed is ERBB2; the disease is invasive breast carcinoma.