Genetic testing for breast cancer is very necessary. Generally speaking, knowing the expression of breast cancer genes has several implications, as follows: first, to know whether there are genetic genes for breast cancer: for example, the common BRCA1 and BRCA2 genes. Second, to determine the degree of differentiation and grading of breast cancer: that is, to understand the severity of breast cancer. Third, to determine the prognosis: for example, the cure rate, recurrence rate, mortality rate, etc., to understand some information in this regard. Fourth, to guide the use of drugs: for example, there are therapeutic drugs for HER-2 gene expression positive, such as Herceptin, which has changed the traditional mode of breast cancer drug treatment, giving a chance to cure early breast cancer and also reducing the risk of recurrence by 50%. Therefore, genetic testing for breast cancer is very necessary to help patients to determine a more accurate and appropriate treatment plan, thus improving the effectiveness of treatment.