As a charity, we rely on voluntary contributions to provide this information. Hormones are substances that occur naturally in the body, where they act as chemical messengers and help control the activity of cells and organs. Formestane is a synthetic hormone. Formestane is given as an injection onto the buttock once every two weeks.
Many breast cancers rely on supplies of the hormone oestrogen to grow.
In women who have passed the menopause the main source of oestrogen is through the conversion of other hormones produced by the adrenal gland to oestrogen. This is carried out by an enzyme called aromatase, mainly in the fatty tissues. Formestane works by inhibiting the aromatase enzyme and preventing this chemical change. This results in a reduction in the amount of oestrogen in the body. Each person's reaction to any medication is unique.