Women with hormone-sensitive breast cancer cells have hormone receptors that become activated when hormones bind to them. The activated receptors lead to specific changes in gene expression and may lead stimulation of cell growth.
Before the doctor would decide to initiate hormone therapy, he would determine the responsiveness to hormones and might suggest a test for the same. A tumor cell which contains estrogen receptors is called as estrogen receptor-positive (ER-positive), estrogen-sensitive, or estrogen-responsive and tumor cells containing progesterone receptors is called as progesterone receptor-positive (PR- or PgR-positive).
Hormone therapy is usually are recommended when these receptors are sensitive and would aims at slowing down or stopping the growth of hormone-sensitive tumors by blocking the body’s ability to produce hormones or by interfering with hormone action. It is essential to understand that tumors that do not contain hormone-sensitive receptors do not respond to hormone therapy. It is a systemic therapy and would be distributed in the entire body and not just localized to breast. It is most often used as an adjuvant therapy to prevent the chances of cancer coming back and can be used post and pre surgery. In some cases, it can be used to treat cases when cancer has metastasized and has come back.
There are several different types of hormone therapies that work on the basic principle of lowering estrogen levels or stopping estrogen from acting on breast cancer cells. Majority of drugs work to block estrogen receptors like tamoxifen. This is usually prescribed pre menopause and for most of the breast cancer cases. When the tumor has spread to other parts, Fulvestrant may be prescribed. It works when all other treatment alternatives have failed.
Drugs like aromatase inhibitors stop estrogen production and are most useful in women who are past menopause. Under extreme cases, ovarian ablation might be used for breast cancer treatment. This involves shutting down the making pre-menopausal women post-menopausal and ensuring better working of treatments like aromatase inhibitors. This is usually done under extreme conditions.