Hormone receptors and breast cancer.
The hormones of reproduction have been implicated in breast cancers of women. A short reproductive life, and a pregnancy prior to the age of 30 years, both reduce the risk of breast cancer (Doll, 1975). In addition, removal of endogenous sources of oestrogens, and administration of anti-oestrogens, cause some breast cancers to regress (Stoll, 1969). Such observations have led to an investigation of the role of the hormones of reproduction, and of oestrogen in particular, in the maintenance of breast cancers.