Recently, Hollywood actress Angelina? Jolie made a big announcement in the New York Times: based on the results of her breast cancer genetic test, she found out that she is a congenital BRCA1 gene defective with a 65% lifetime risk of breast cancer, so she had a total mastectomy and reconstructive surgery and urged women with a genetic predisposition to take proactive measures. What made this actress determined to have her breasts removed? We would like to interpret the medical information behind this news story through professional eyes. Is breast cancer hereditary? This is a question that many people often ask. Some patients also have the question: if they already have breast cancer, are their sisters or daughters at risk of developing cancer? Recent studies have been able to answer these questions: breast cancer, like most malignant tumors, occurs due to a combination of environmental and genetic factors. Genetic factors account for only a small part of the mechanism of breast cancer development. Some studies have shown that hereditary breast cancer accounts for 5-10% of all breast cancers, which is only a relatively small percentage of all breast cancer patients. How is breast cancer inherited? This is a rather specialized question, so we will give a brief answer here. As you know, half of a child’s genetic material comes from the father and half from the mother, and if either parent has a defect in the genetic material, it can be passed on to the child. It has now been confirmed that the occurrence of hereditary breast cancer is associated with these defects in genetic material, which means that people with defects in genetic material are prone to breast cancer, so breast cancer is passed on to the next generation through the transmission of genetic defects. Such genetic defects have been identified in white women, most commonly mutations in the BRCA1 and BRCA2 genes, and women carrying such defects have a much higher risk of developing breast cancer than the general population. Therefore, testing for these genetic defects in people at high risk of breast cancer is beneficial for early diagnosis and prevention of breast cancer. What kind of breast cancer patients are likely to be hereditary? There are certain characteristics of hereditary breast cancer, which often manifest as early onset, family aggregation, etc. Early onset refers to the early onset of breast cancer, which may occur at the age of less than 35 years old; familial aggregation refers to the fact that two or more members of the family with blood relationship are breast cancer patients, sometimes combined with other malignant tumors, such as ovarian cancer, prostate cancer, stomach cancer, etc. A study conducted by Fudan University Cancer Hospital in a specific high-risk breast cancer population (familial breast cancer and/or breast cancer with age of onset less than 35 years) tested for the most common breast cancer susceptibility genes, BRCA1 and BRCA2, and found that hereditary breast cancer was found in up to 10% or more of these specially selected breast cancer patients. What should I do if I am highly suspicious of a patient with hereditary breast cancer or if it is clear that I have hereditary breast cancer? If this is the case, then the biggest problem is that healthy members of the family who are related to the patient may also carry the disease-causing gene mutations, and women who carry these mutations have a much higher lifetime risk of developing breast cancer, with the BRCA1 and BRCA2 genes, for example, having a 60-70% lifetime risk of cancer in mutation carriers. As we know, the most effective way to prevent breast cancer is to have a breast screening. Generally speaking, the age of mammogram screening for healthy women is around 40 years old. However, because of the early onset of hereditary breast cancer, the screening age for these healthy women who are highly suspected or clearly carry genetic mutations needs to be advanced by at least 10 years, and it is generally recommended to start screening at around 25-30 years of age using diagnostic breast imaging methods. In addition, because of the dense breast tissue in young women, the use of mammography is often ineffective, and recent studies have shown that magnetic resonance imaging (MRI) has a role in breast screening in these women that is superior to that of mammography. Therefore, MRI is necessary for early screening of women at risk. Hereditary breast cancer is not frightening and it represents a small percentage of all breast cancers. What is important is to detect its hereditary nature, which requires proper awareness of cancer prevention and timely medical consultation is very important. Only early detection, early prevention and early treatment can improve the cure rate of hereditary breast cancer.