Breast Cancer Like most malignancies, breast cancer occurs as a result of a combination of environmental and genetic factors. Among the causes of breast cancer development, genetic factors are one of them. Familial breast cancer Familial breast cancer is characterized by family aggregation. It is generally accepted that two cases of breast cancer in a family with related members are considered to be familial breast cancer. For example, a family living together in a highly pathogenic environment may have a high incidence of breast cancer. Hereditary breast cancer Hereditary breast cancer refers to a patient who has an altered genetic material base associated with breast cancer and, in addition, this alteration gains the ability to be passed on to future generations. It is evident that hereditary breast cancer is familially aggregated and hereditary breast cancer is a part of familial breast cancer. Familial breast cancer accounts for 20-25% of all breast cancers, with hereditary breast cancer accounting for 5-10% of all breast cancers. Characteristics of hereditary breast cancer: 1. Early age of onset, accounting for 25%-35% of breast cancers before the age of 30. The proportion of breast cancer in bilateral breast is high. 3. The proportion of other malignant tumors is high. For example, ovarian cancer. 4. Hereditary breast cancer is associated with clear genetic mutations. The most common of them are BRCA-1 and BRCA-2 genes. It is important to find out the hereditary nature of hereditary breast cancer. For women who may have hereditary breast cancer, they should do “hereditary breast cancer risk prediction” if they have the conditions to detect and treat her early.