The FISH result of HER-2 suggests the HER-2 gene expression status of the cancer cells, and those who are positive can be treated with anti-HER-2 therapy. HER-2 gene is an oncogene commonly expressed in breast cancer, and HER-2 positive breast cancer can account for about 1/5 of the total number of breast cancers, and its condition is more aggressive, prone to recurrence and metastasis, and its survival period is relatively short. Currently, immunohistochemistry is routinely performed on breast cancer cells to initially detect the HER-2 expression status of the patient, and if immunohistochemistry suggests that HER-2 is suspected to be positive, then FISH immunofluorescence testing is further performed to determine the HER-2 status of the cancer cells. If the FISH result is positive, it indicates that targeted drugs such as trastuzumab and patuximab can be used as prescribed by the doctor.