One of my favorite topics is back in the news: the relationship between postmenopausal hormone therapyâ€”what we used to call hormone replacement therapy (HRT)â€”and breast cancer.
As you probably recall, in July 2002 a large randomized study called the Womenâ€™s Health Initiative was stopped prematurely found that the risk of taking menopausal hormones outweighed any benefits. Virtually overnight, the number of women taking hormones to treat menopausal symptoms dropped dramatically. And then something incredible occurred: the incidence of breast cancer went down 15%. In other words, 15% fewer breast cancers were diagnosed in one year alone!
Weâ€™ve continued to see a decrease in breast cancer incidence over the past five years. And this decrease also has been seen in other countries besides the US. Yet, the pro-hormone folks have continued to argue that we shouldnâ€™t jump to conclusions, as the reason for the decrease in breast cancer incidence could have been due to a decrease in the number of women who were getting mammograms.
But a study published this week in the New England Journal of Medicine has confirmed that it wasnâ€™t a decrease in mammograms that decreased breast cancer incidence. It was stopping HRT. As the researchers explain, â€œthe increased risk of breast cancer associated with estrogen-plus-progestin therapy declined markedly soon after discontinuation of the therapy and was unrelated to a change in the use of mammography.â€
Furthermore, a second study that came out this week found that menopausal hormones (estrogen plus a progestin) doubled the risk of lobular cancer and increased the risk of ductal cancer by 75%. Furthermore, the longer a woman took hormones, the greater the risk. For ductal cancer, the risk doubled at about ten years, while for lobular cancer the risk doubled within the first five years. The use of estrogen alone (which is taken by women who no longer have a uterus) also increased breast cancer risk, but only by 50% after ten years.
The good news is that there did appear to be a safe period in which women can be on hormones and not experience an increased breast cancer risk. But that â€œsafeâ€ period is only about two years. Both studies also found that the increased risk disappeared within two years of women stopping the drugs.
Menopause is programmed into our bodies. We need high levels of hormones to reproduce, and then, when we reach menopause, our hormones shift down to a safer level. The bottom-line has been reinforced: Artificially maintaining higher levels of hormones is not good for our health.