Breast cancer is the most common malignancy among women in China. About 7% of breast cancer patients in developed countries are younger than 40 years old and are diagnosed with breast cancer. The earlier age of breast cancer onset may be associated with more malignant biological behavior and worse prognosis. Most scholars currently define breast cancer that occurs under the age of 40 as young breast cancer. There are many risk factors for breast cancer, which can be summarized as non-genetic factors and genetic factors. Non-genetic factors include birth weight, growth rate and acquired height, long-term animal fat intake, long-term oral contraceptive use, early menarche, late age of first full-term pregnancy, breastfeeding, low body mass index, history of chest cape field radiation treatment at young age, dense breast and previous history of atypical hyperplasia. 2. The usefulness of breast cancer risk prediction models for young high-risk groups Young breast cancers have a significantly higher rate of clinical underdiagnosis than older breast cancers due to many factors such as their own lack of attention and dense breasts. Current screening strategies do not support universal screening for those under 40 years of age. Therefore, it is particularly important to use breast cancer risk prediction models to identify young people at high risk for breast cancer and to focus on surveillance. Breast cancer risk prediction models can predict the risk of breast cancer by weighting together many risk factors associated with breast cancer, and predict the risk of genetic mutations, as well as determine whether closer follow-up is needed, which is very helpful for identifying young breast cancer high-risk susceptible groups and focusing on screening. Genetic testing is also an effective way to identify young breast cancer patients who are at high risk of developing the disease. Genetic testing should be performed in young people who are clinically suspicious or have high risk assessment model scores. The NCCN recommends genetic testing for the following groups of young people: family members with breast cancer-related mutations, family members with two or more primary cancers of the breast, paternal or maternal family members with two or more primary cancers of the breast, one or more ovarian cancer patients, first- or second-degree relatives with breast cancer younger than 45 years of age, one or more relatives with breast cancer associated with one or more other cancers, such as concurrent thyroid cancer, diffuse gastric cancer, endometrial cancer, and male breast cancer. Genetic disorders known to be associated with younger breast cancer incidence include hereditary breast ovarian cancer syndrome due to BRCA mutation, Li-Fraumeni syndrome due to TP53 mutation, Peutz-Jeghers syndrome due to STK11 mutation, Cowden syndrome due to PTEN mutation, and hereditary diffuse gastric cancer syndrome due to CDH1 mutation. Gastric cancer syndrome due to CDH1 mutation, etc. Genetic testing is useful to identify young people at risk for mutations and to provide early monitoring and intervention. It is important to note that about 10% of breast cancers have a tendency to cluster in families, but some of these populations are known to be negative for the target gene. Therefore, if there is a tendency of family clustering in young people with negative genetic test, they are still in the high-risk group. 4. Screening strategy for young high-risk susceptible population There is no evidence of universal screening for breast cancer in the young population, but close surveillance is needed for the identified young high-risk susceptible population of breast cancer. The primary means of surveillance include mammography and MRI. The American College of Radiology (ACR) recommendations for mammography screening in asymptomatic, high-risk young women under 40 years of age are: for those with BRCA1 and BRCA2 mutations, begin annual mammography screening between the ages of 25 and 30 years, but no earlier than 25 years of age; for those who are not tested but have a BRCA2 mutation, begin annual mammography screening between the ages of 25 and 30 years. For those who are not tested but have a first-degree relative with a known BRCA mutation, annual mammography screening should be initiated between 25 and 30 years of age, but no earlier than 25 years of age. Patients with a lifetime probability of cancer greater than 20% as calculated by the breast cancer risk model should begin annual mammography screening between the ages of 25 and 30 years, but no earlier than 25 years, or the youngest first-degree relative with cancer minus 10 years, whichever is later; those who received radiation therapy to the chest cape field between the ages of 10 and 30 years should begin Annual mammogram screening was initiated 8 years after the end of radiation therapy, but no earlier than 25 years of age. For biopsy-proven lobular neoplasia, atypical hyperplasia, ductal carcinoma in situ, invasive carcinoma, or ovarian cancer, annual mammography screening from the date of diagnosis, regardless of age. For those with dense breasts on mammography, the addition of ultrasound screening can increase the detection rate of breast cancer, and ultrasound has some advantages for Chinese women with relatively dense breasts. The NCCN states that MRI screening is recommended for those with BRCA mutations, first-degree relatives with BRCA mutations who have not been tested, or those with a family history-based risk model suggesting a lifetime risk of cancer greater than 20%, or those with a history of radiation therapy to the chest between the ages of 10 and 30. MRI is not recommended for those who have less than 15% risk. Chemoprevention in young high-risk groups Chemoprevention refers to the reduction of the incidence of breast cancer through the administration of chemical drugs to specific groups of people. Chemoprevention can be considered for young people who are at high risk of breast cancer. Chemoprevention in young people at high risk of breast cancer is mainly referred to as selective estrogen receptor modulator (SERM) tamoxifen. The US Adjuvant Breast and Bowel Surgery Study Group reported a 49% reduction in the risk of invasive breast cancer in people at high risk of breast cancer with tamoxifen at a dose of 20 mg/d orally for 5 years compared to placebo. The European International Breast Cancer Intervention Study reported a 31% reduction in the risk of ER(+) breast cancer in people at high risk for breast cancer when tamoxifen was administered orally for 5 years. Goss et al. reported that 35 months of oral exemestane reduced the risk of invasive breast cancer by 65%. Cuzick et al. reported results from the International Breast Cancer Intervention Study of anastrozole for the prevention of breast cancer in a high-risk postmenopausal population, which showed a 53% reduction in breast cancer risk in the anastrozole group. Fagerlin et al. showed that 50% of women refused to take tamoxifen for breast cancer prevention with prior knowledge of adverse effects. Unlike the high-risk group of breast cancer identified in old age, the young breast cancer risk group has a significantly higher probability of developing breast cancer during their lifetime than the elderly because of their longer life expectancy. Therefore, for young high-risk patients who have already had breast cancer on one side, prophylactic mastectomy of the opposite breast may be considered. This article focuses on prophylactic bilateral mastectomy in young high-risk patients. Prophylactic bilateral mastectomy in young high-risk patients can reduce the risk of breast cancer by more than 90% for most of their lives, eliminate the need for imaging surveillance, reduce psychological anxiety in high-risk patients, and provide more options for breast reconstruction. The NCCN committee supports consideration of prophylactic mastectomy for patients with highly predisposing genetic mutations (e.g., BRCA1 and BRCA2 mutations, Cowden’s syndrome, Li-Fraumeni syndrome, Peutz-Jeghers syndrome) and a significant family history of breast cancer, and prophylactic mastectomy for patients with lobular carcinoma in situ may be an Prophylactic mastectomy is an option but not recommended for patients with lobular carcinoma in situ, and there is no evidence on whether to perform prophylactic mastectomy in patients who have undergone breast radiation therapy before age 30. Due to the specificity of the breast as a female aesthetic organ and the presence of post-excisional changes in appearance, complications of breast reconstruction, and failure to meet expectations for reconstructive outcomes, individualized treatment based on patient wishes is essential. After a thorough risk assessment and adequate information about the advantages and disadvantages of surgery, it is a clinically advocated practice to let patients make their own decisions. 7. In conclusion, this paper has detailed the management strategies for young breast cancer high-risk susceptible population from different perspectives, including identification, risk modeling, genetic testing, screening, chemoprevention and surgical prevention. For this population, early identification, regular surveillance, and early prevention are necessary to have the greatest clinical benefit.