In one of the largest long-term studies of its kind researchers from across the UK collected data from 534 postmenopausal women. Before the study began, 364 of the women had taken oestrogen and progestogen hormone replacement therapy in which the two hormones were given sequentially, 164 had not used hormone replacement therapy and 10 had taken oestrogen only hormone replacement therapy.
The women were placed on a course of continuous combined HRT. Biopsy samples were then taken from the women before they started to take the combined HRT, after nine months, and between 24-36 months and at the end of the five year study.
Before the research began, 21 women were noted as having abnormal endometrium, which when associated with other cellular changes can be an early sign of cancer, but following nine months of continuous combined HRT, the endometrium had reverted to normal. No cases of endometrial cancer developed during the study.
Women who take daily combined HRT may actually be better protected against endometrial cancer than women who do not use any form of hormone replacement therapy, they conclude.