ERDs (Estrogen-Receptor Downregulators)

Estrogen receptor downregulators, called ERDs for short, block the effects of estrogen in breast tissue. ERDs work in a similar way to SERMs, such as tamoxifen. ERDs sit in the estrogen receptors in breast cells. If an ERD is in the estrogen receptor, there is no room for estrogen and it can't attach to the cell. If estrogen isn't attached to a breast cell, the cell doesn't receive estrogen's signals to grow and multiply. ERDs also:

• reduce the number of estrogen receptors
• change the shape of breast cell estrogen receptors so they don't work as well

There is one ERD available to treat hormone-receptor positive breast cancer:

• Faslodex (chemical name: fulvestrant)

See the Faslodex page for information on who it's for, benefits, and side effects.