1.Why do we need genetic testing? We know that genes are the genetic material of human beings. Mutations in genes may cause certain diseases, including breast cancer. This is what we call breast cancer is related to heredity. Modern sequencing technology can detect abnormal mutations in an individual’s genes and compare them with past databases to predict whether she is likely to develop hereditary breast cancer in the future. Genetic testing is already relatively popular in Europe and the United States, but it is just beginning in China. 2.How to detect genetic abnormalities? Genes are stored in the nucleus of cells, so to do genetic testing you need to get human cells first. The classical method is to take 2~4ml of blood and extract genes from the blood cells for sequencing. Nowadays, genes can also be extracted from the exfoliated cells in saliva for testing. The Breast Center of Peking University People’s Hospital can now provide testing technology for the above methods through cooperation with genetic testing companies. 3. Do I need to have a preventive mastectomy if the gene is found to cause the disease through genetic testing? Since Angelina Jolie underwent a prophylactic bilateral mastectomy due to the discovery of a genetic mutation, this issue has received increasing attention. Indeed, if a definite genetic mutation is found, the lifetime risk of breast cancer can be 40% to 70%, while prophylactic mastectomy can have a 90% success rate of prevention, making it a more traumatic but acceptable treatment in the West. Unfortunately, however, genetic testing in China has not started for a long time, and the critical issue of the likelihood of disease-causing genes causing breast cancer in Chinese women is not yet clear, so it is not yet advisable for women carrying mutated genes to blindly choose prophylactic excision. For now, more detailed imaging screening is recommended for early detection of breast cancer in women with genetic abnormalities. Of course, for women with a clear family history, a mutation, and a particularly stressful psychological condition, prophylactic excision may be a good option, but it does require weighing the pros and cons.