The immunohistochemistry results of breast cancer mainly look at four indicators, namely ER, PR, HER-2 and KI67, and are analyzed and judged comprehensively by professional doctors. Generally after the diagnosis of breast cancer, immunohistochemistry examination is needed after surgery, which mainly analyzes and judges from the four indexes of ER, PR, HER-2 and KI67. Among them, ER represents estrogen receptor, PR represents progesterone receptor, HER-2 represents targeted therapy target, and KI67 represents cell proliferation index. If the ER and PR indicators are positive, it means that breast cancer is related to the excessive secretion of estrogen and progesterone in the body, and it is necessary to take endocrine drugs as soon as possible under the guidance of a professional doctor to inhibit the secretion of estrogen and progesterone. If HER-2 (+), it is negative. If it is HER-2 (++), it should cooperate with professional doctors to improve FISH test to further determine whether HER-2 is positive or negative. If HER-2 (++++), it is positive and requires targeted therapy. The purpose of doing immunohistochemistry after breast cancer surgery is to determine the appropriate treatment from these indicators, such as endocrine therapy, targeted therapy or other treatments, etc., which will provide a reference basis for the follow-up treatment.