Question: How can my breast cancer be estrogen receptor-positive when I am postmenopausal and my body is losing estrogen?
Answer: This is a very interesting question. Estrogen receptor positivity in fact increases in post-menopausal woman. Now this seems rather unusual to most people because the ovaries may have stopped producing estrogen. But that's not the issue. In post-menopausal women, body fat still produces estrogen, and in fact these low levels of estrogen really produce all of the driving forces for the cancers to grow. In this low estrogen environment, the breast cancer is very clever. What it does is expand the number of locks -- the estrogen receptors -- inside the tumor so it can capture these very, very small levels of estrogen. So estrogen receptor values tend to be higher in post-menopausal women than in pre-menopausal women. So estrogen is still made and is still very dangerous for the post-menopausal woman.