Combined oestrogen/progestin HRT for more than two years increased older women’s risk of developing breast cancer, reported the Women’s Health Initiative study in 2002. A follow-up study which followed the health outcomes of the same women confirmed the finding. Two years after coming off HRT the women’s risk of developing breast cancer had returned to normal.

Some researchers (perhaps HRT enthusiasts for various reasons) have suggested that both the increase and later decrease in breast cancer cases might be due to differences and changes in the frequency the women had had mammograms. Not so, according to the follow-up study. Mammogram frequencies were similar in both the HRT and control groups during both the initial study and the follow-up.

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