Why are hormones so significant in their relation to breast cancer?

Because they are derived from normal cells that have hormone receptors and the normal cells must respond to hormones in order to fulfil their function. A high proportion of breast cancers are Estrogen Receptor Positive. This means they have a large number of estrogen receptors, indicating that estrogen is helping to feed their growth.

Receptors are proteins in or on certain cells that can attach to certain substances, such as hormones, that circulate in the blood. Normal breast cells and some breast cancer cells contain receptors that attach to estrogen and progesterone. These 2 hormones often fuel the growth of breast cancer cells.

Breast cancer that involves estrogen and progesterone receptors is likely to respond to treatments known as “endocrine therapies”. In medicine, drugs such as Tamoxifen are used to block the estrogen receptors and help prevent the cancer from recurring. In post-menopausal women, drugs called aromatase inhibitors may be more beneficial to help stop production of estrogen.