The multiplication of certain types of malignant cells is hormone-dependent. This applies particularly to breast and prostate cancer.
Hormone therapy works by blocking the body’s own hormones to prevent them from stimulating the cancer.
With breast cancer, oestrogens are blocked and, in the case of prostate cancer, androgens are blocked.
One method involves blocking the activity of the hormone within the tumour, as with tamoxifen and the peripherally acting anti-androgens.
Alternatively, ovarian and testicular secretion of hormones may be blocked. To do this one may administer radiotherapy to the ovaries or employ surgery to remove the ovaries (oophorectomy) or part of the testes (pulpectomy).
Secretion can also be blocked by means of drugs which are injected subcutaneously (LHRH analogues).
Finally, there is a novel mechanism of action which consists of blocking hormones by preventing their conversion within the body (the family of anti-aromatase drugs). At present, this method is confined to breast cancer.
Sometimes it is possible to use progesterone as hormone therapy.