What Is Hormonal Therapy for Breast Cancer?

Dr. William Gradishar answers the question: 'What Is Hormonal Therapy?'

— -- Question: What is hormonal therapy?

Answer: Hormonal therapy, or otherwise known as endocrine therapy, is an approach for certain patients with breast cancer. It has always been our belief that a significant fraction of patients develop their breast cancer because of the influence of hormones, and often specifically, estrogen. Hormone therapy can often be confused -- when we think of therapy -- with oral contraceptives or hormone replacement therapy that is commonly used in post-menopausal women.

But when we talk about endocrine or hormonal therapy as a treatment for breast cancer, we're talking about a different class of drugs; we're often talking about anti-estrogens such as tamoxifen, aromatase inhibitors such as anastrozol, Letrozole, or exemestane -- and really, the strategy is to focus on what stimulates a breast cancer to grow. So in patients that have breast cancers that have estrogen and progesterone receptors present -- which is the majority of breast cancers, but not all -- these are breast cancers that are potentially influenced by estrogen in the body.

So treatment strategies focus on one of two things: either to block the effect of estrogen on the receptor present on a breast cancer cell -- and that is called an 'anti-estrogen' because it blocks the effect of the estrogen on the receptor present in the tumor cell -- or to actually decrease the manufacture of estrogen in the body -- and this is accomplished by using drugs like aromatase inhibitors. So you can attack the tumor cell, in a sense, from blocking the effect of estrogen through blockage of the receptor on the breast cancer cell, or you can actually try and stimulate the body to block the synthesis of estrogen, using an aromatase inhibitor.

There are also other hormonal strategies such as drugs that block or interrupt the pathway from the brain to the ovaries, which in a sense, is another way of decreasing the synthesis or manufacture of estrogen by the ovaries. So hormone therapy, as a strategy, is meant to block the effects of estrogen on a tumor cell -- either by decreasing the synthesis of estrogen or blocking the effect of estrogen on an established tumor cell.

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