In our clinical work it will be easy to find that a patient with breast cancer in the family may have relatives with the same disease. In fact, many cancers and chronic diseases have a tendency to run in families, and breast cancer is no exception; it also has a clear tendency to run in families. According to epidemiology, we can find that 5% to 10% of breast cancers are familial, the risk of the disease increases 1.5 to 3 times in common relatives, and the prevalence of breast cancer in close relatives will increase 7 times. Especially, the younger the age of onset, the greater the risk of breast cancer among relatives, so we should be more alert. Because currently, there is a trend of younger breast cancer patients in China.