The history of hormone therapy

Hormones are chemical messages produced by some parts of the body that cause changes in other parts. For example, the ovaries produce the female sex hormone oestrogen, while the pancreas produces insulin, which affects how we absorb glucose from the blood.

We now know that hormone systems are implicated in some types of cancer; for example, oestrogen encourages some types of breast cancer to grow faster. By tinkering with the body's hormone system in the right way, doctors can stop some cancers growing and even kill them.

In 1896, George Beatson, a Glasgow surgeon, published details of three patients whose advanced breast cancer had responded favourably to oophorectomy (removal of the ovaries). This was the first hint that the hormone system was involved in cancer growth. Beatson's work led scientists to look for ways to block oestrogen's tumour-promoting activity.

By 1937, Dodds & Robinson had invented a chemical called diethylstilboestrol, which showed anti-tumour activity in an MRC trial in 1939. However, the high doses required produced severe side effects. Despite this, the drug became the drug of choice for prostate cancer a few years later.

In 1969, the synthetic oestrogen-blocker tamoxifen was first used to treat breast cancer at the Christie Hospital in Manchester. Tamoxifen is now widely used in breast cancer treatment, and Cancer Research UK has been at the forefront of research into the drug's effectiveness.

In 2002, a Cancer Research UK study, IBIS I, showed that tamoxifen could also be used to prevent breast cancer in high-risk post-menopausal women. However, tamoxifen is not without side effects, so Cancer Research UK is now looking at another anti-oestrogen drug, arimidex, in a study called IBIS II. Arimidex seems to be as effective as tamoxifen, but causes fewer side effects.

Other hormone-based therapies in use today include cortisone, used to treat some leukaemias and lymphomas, and ' androgen-ablation therapy' (which uses drugs to lower the amount of the male sex homone testosterone) to treat prostate cancer.