First, can you give us a general definition of hormonal therapies for breast cancer, and explain how they work?
The term hormonal therapy describes a number of different treatment approaches, but the underlying idea is to reduce the supply of estrogen to the tumor. We can accomplish this in a number of ways by using various hormonal manipulations. The SERMs, or selective estrogen receptor modulators, interfere with estrogen at the level of estrogen receptor binding, and tamoxifen is the best known drug in this class.
The aromatase inhibitors are another class of drugs that reduce blood levels of estrogen in postmenopausal women. These drugs inhibit the production of estrogen that takes place in the muscle and fat of women that continues after menopause. In premenopausal women, estrogen production happens mainly in the ovary, and reducing ovarian estrogen production in these women can serve as a treatment for breast cancer. This can be accomplished by either surgery or medication (e.g. the LHRH-agonists).
And why does estrogen play such a central role in breast cancer?
Well, about two thirds of breast tumors 'express', or make, the estrogen and/or the progesterone receptor. A tumor that's estrogen or progesterone receptor positive is considered 'hormone sensitive', and women who have these tumors have the option of hormonal therapy for both the treatment of early stage and metastatic cancer.
