Hormone raises breast cancer risk

Incidences of breast cancer are higher in developed countries

A university lecturer has claimed high levels of the hormone oestrogen may be making women in richer countries more prone to breast cancer.

Studies have shown that western women have very high levels of the female hormone compared with those of their ancestors or people in underdeveloped countries.

Dr Tessa Pollard, a lecturer in biological anthropology at the University of Durham, said it could be one reason why so many women in countries such as the UK develop breast cancer.

Oestrogen is known to fuel most types of breast cancer but it also protects women from heart disease up to the menopause.

Dr Pollard told the British Association Festival of Science at the University of Salford on Tuesday that oestrogen levels vary.

Saliva test

Researchers looking at women in "traditional" communities had found that they produced less oestrogen over a lifetime than those in modern societies because they menstruated less.

One study showed that Dogon women in Mali, west Africa, experienced an average of 109 periods in a lifetime, compared with a western woman's 400.

In addition, women in richer countries today had their first period earlier than those in poorer countries and had the menopause later.

Another study, of Lese women in the Democratic Republic of Congo, measured the saliva levels of oestrogen during menstrual cycles.

It showed that they had much lower levels of oestrogen than a comparison group of women from Boston in the United States.

Dr Pollard said: "Why do so many women in countries like the UK get breast cancer? What is it that protects women, particularly after the menopause, from heart disease?

"It seems likely that oestrogen is a big part of the answer to these questions."