Specifically, the methylation level ofthe RANBP3 gene exhibited a more pronounced tendencyto change in estrogen receptor-expressingbreast cancer, while the methylation level of the LCP2gene was associated with tumour malignancy.Moreover, cfDNA from breast cancer patients exhibiteda methylation pattern of these three genes thatmirrored that of cancer tissue. The gene discussed is ESR1; the disease is breast carcinoma.