Described are epigenetic biomarkers of breast cancer and their use in breast cancer screening and diagnosing, or to provide disease prognosis in a subject. The epigenetic biomarkers include methylatable regions (MRs), which may be at least one segment from nucleic acid sequences represented in Table 1. Described are also methods of detecting the methylation level of MRs in the subject, the methylation score (mSCORE) of the subject, and using these values to evaluate a breast cancer risk in a subject, or diagnose a subject with breast cancer. Also described are methods of determining a risk of recurrence and disease prognosis in a subject undergoing or having undergone a treatment for breast cancer.