What is Hormone Replacement Therapy?

• Hormone Replacement Therapy (HRT) involves taking female sex hormones to replace declining levels as a woman goes through the menopause. 
• HRT works by providing oestrogen, with or without added progesterone, to supplement the lower levels produced by the body at menopause.
• Hormone Replacement Therapy is prescribed mainly to relieve unpleasant menopausal symptoms such as hot flushes, vaginal dryness and night sweats. It may also be used for longer-term prevention of osteoporosis in post-menopausal women who are unable to take other osteoporosis prevention treatments.
• HRT is available as tablets, implants, patches, vaginal rings, skin gels, oestrogen injections and nasal sprays. There are also vaginal preparations such as creams, tablets or pessaries (suppositories).

Concerns with HRT

Two major studies, the Women’s Health Initiative (WHI) and the Million Women Study (MWS) have provided evidence that the use of Hormone Replacement Therapy increases the risk of breast cancer, endometrial cancer and ovarian cancer in a duration-dependent manner. There is also no evidence for a beneficial effect of HRT on cardiovascular disease – in fact HRT has been shown to increase the risk of heart attack, especially in the first year of use, and to increase the risk of stroke. The risk of most of these conditions increases with age, therefore increasing the overall risks the longer HRT is taken.

• The WHI was launched in 1991, begun in 1997 and scheduled to be completed in 2005. It involved more than 16,000 healthy post-menopausal American women with a uterus between the ages of 50 and 79 who were randomly assigned to either the hormone medication being studied or to placebo. However, researchers halted the study midway on May 31, 2002 because they felt that the health risks for participants taking HRT outweighed the possible benefits of Hormone Replacement Therapy.
• The Million Women Study was set up to investigate the effects of specific types of Hormone Replacement Therapy (HRT) on incident and fatal breast cancer. 1,084,110 UK women aged 50–64 years presenting for breast screening were recruited into the Million Women Study between 1996 and 2001, provided information about their use of HRT and other personal details, and were followed up annually for cancer incidence and death.