How FASLODEX works

The role of hormones and breast cancer

The hormones estrogen and progesterone play an important role in the growth, development, and function of breast cells. These hormones are naturally produced by organs in the body. To receive the signals from these hormones, normal healthy breast cells have estrogen receptors and progesterone receptors associated with them. The hormones attach to these hormone receptors.

The breast cancer cells of many women diagnosed with breast cancer will have receptors for estrogen and/or progesterone. When they do, the breast cancer is said to be hormone receptor-positive. When breast cancers are estrogen receptor positive, estrogen may contribute to the growth and spread of the cancer.

How FASLODEX affects estrogen receptors

FASLODEX is a hormonal therapy that works by binding to estrogen receptors. In doing so, FASLODEX can block the effect estrogen has on the cancer cells. FASLODEX also causes the estrogen receptor to change shape and not work as well. In addition, FASLODEX causes a decrease in the number of estrogen receptors.

See how FASLODEX works

Here's a simple way to think about how FASLODEX works in your body. Note: images are not actual depictions, but rather visual representations.

Imagine many keys and many locks. Estrogen in the body represents keys, and estrogen receptors in the cancer cell are locks.

If a key (estrogen) enters a lock (estrogen receptor) and opens it, estrogen can enter and possibly cause the breast cancer cells to grow and multiply.

FASLODEX plugs up the lock and changes it so that the key (estrogen) won’t fit properly.

FASLODEX also reduces the number of locks (estrogen receptors) in breast cancer cells.

To find out if your tumor may respond to FASLODEX, your doctor can do a test to determine if your tumor is hormone receptor-positive. Breast cancer tumors are hormone receptor-positive in more than 60% of postmenopausal women.

Learn about taking FASLODEX