A significant difference in cfDNA levels was only seen among BC patients according to their nodal status (64.9 (36.9–156.0) ng/mL vs. 50.7 (0.0–120.0) ng/mL; p = 0.04), but not age (p = 0.73), tumor size (p = 0.09), pathologic stage (p = 0.48), estrogen (ER; p = 0.72), progesterone (PR; p = 0.88), or human epidermal growth factor (HER; p = 0.51) receptor status. Here, ESR1 is linked to neoplasm.