A report presented at the recent San Antonio Breast Cancer Symposium suggested that oestrogen-only hormone replacement therapy (HRT) may reduce the risk of breast cancer in some women. This report has not yet been peer-reviewed so the findings are considered to be preliminary.
The findings were based on existing data from the oestrogen-only arm of the Women's Health Initiative (WHI) study, first published in 2004. This part of the study involved postmenopausal women who had already had a hysterectomy taking oestrogen without progesterone. (This is only possible in women without a uterus because oestrogen by itself can cause an increased risk of endometrial cancer.) International experts have been quick to respond to this new interpretation of the data, with the International Menopause Society (IMS) releasing a statement on their website:
"The recent re-analysis of the WHI data is reassuring to both women and physicians that women at low risk for breast cancer do not increase the incidence of breast cancer while using conjugated oestrogen-only therapy." However the statement does make very clear that any decision to use HRT should be made on a case-by-case basis. "The position of the International Menopause Society is that counselling and the decision regarding the use of any hormone therapy be based on an individual risk-benefit assessment of the woman by her physician."