How do the hormones work?
Estrogen and progesterone travel through the bloodstream and find their matching receptor sites on both healthy cells and cancer cells. Receptors are very specialized protein molecules that sit on the outside or inside of the cells in your body. They act like an on–off switch for a particular activity in the cell. If the right substance comes along that fits into the receptor—like a key fitting into a lock—the switch is turned on and a particular activity in the cell begins. Many breast cancers are hormone-dependent—which means that estrogen and progesterone stimulate their growth by \”turning on\” hormone receptors in the cancer cells. Without these hormones, the cancer cells are not stimulated to grow. They wither, and eventually they may die.
