Breast cancer OFS is a method in the field of breast cancer treatment, where OFS stands for ovarian function suppression. Thus, OFS refers to the suppression of ovarian function, preventing the ovaries from releasing sex hormones, thereby achieving the purpose of treating breast cancer. There are three methods of OFS. The first method is direct surgical removal, medically also called castration. Here, "castration" implies the removal of ovarian influence, and this surgical method is actually one of the most effective methods of OFS. The second method is chemical castration. The most commonly used drug for this is called Gosserelin, which is used for drug-induced ovarian function suppression. The third method of ovarian function suppression is radiotherapy. However, because it is difficult to achieve the desired results and it can cause serious complications, this method is basically no longer used. OFS is necessary for breast cancer patients who are positive for estrogen receptor ER and progesterone receptor PR, and it is used only under these conditions.