There are also differences among the several common genes, and according to AUC, the diagnostic value of cfDNA for PIK3CA and TP53 is higher than ESR1. This study suggests that for the patients with ABC, the detection of genetic mutations by cfDNA has a high utility of being used as a surrogate of tissue DNA, yet reliable results cannot be obtained in EBC patients because of the obvious heterogeneity. The gene discussed is ESR1; the disease is aneurysmal bone cyst.