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The Collaborative Group on Hormonal Factors in Breast Cancer has brought together the worldwide evidence on menopausal hormone therapy (MHT) and the incidence of invasive breast cancer. All types of MHT examined, except vaginal oestrogens, were associated with a significant excess incidence of breast cancer. Both among current users and among past users the risks increased steadily with duration of MHT use. Risks were greater for oestrogen-progestagen than for oestrogen-only preparations, and some excess risk persisted for more than a decade after cessation of use. The collaboration collected no information, however, on breast cancer mortality.
This recent study adds to the world literature on this subject.

It has been well recognised for many years that breast cancer risk is slightly increased for women on HRT and that Oestrogen alone has a smaller effect than combined Oestrogen and Progesterone therapy.

The increased risk is small as we would expect. For whilst breast cancer is hormone sensitive it is multifactorial in origin with genetics, life-style issues such as increased BMI and excessive alcohol intake being major determinants.

It remains logical that longer Oestrogen and Progesterone exposure would lead to a small increase in breast cancer.

It must not be forgotten that HRT relieves the awful symptoms that many women suffer when they reach the menopause and that these symptoms may persist for years. HRT is also cardio-protective and when taken soon after the menopause reduces the risk of cardiovascular events.

Before starting HRT women should be carefully informed of all the issues surrounding HRT so that they can make an informed choice about whether or not they wish to take it and for how long.