One of my favorite topics is back in the news: the relationship of postmenopausal hormone therapy (previously known as hormone replacement therapy) and breast cancer.



Most women have heard the controversy surrounding hormones and the concern that they may increase breast cancers. The real proof came, I think, the year that the large randomized Women’s Health Initiative was stopped prematurely because the risks of hormones outweighed the benefits. Suddenly, the number of women taking hormones dropped and so too did the incidence of breast cancer -- by an astonishing 15%. That means 15% fewer breast cancers were diagnosed in one year!



That decrease has persisted but the pro hormone folks have argued that there could have been something else going on, like a decrease in screening mammograms, for example. Recently, the New England Journal of Medicine came out with the answer: It wasn’t a decrease in mammograms that made the difference, but stopping hormone replacement therapy. They clearly demonstrated in two studies (read here) that “the 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.” The increase started after about two years and the decrease started almost immediately and was back to normal within two and a half years.



A second study (read here) that came out the same week looked at the risk for menopausal hormones (estrogen plus a progestin) more closely, finding that the risk of lobular cancers (harder to detect) doubled with hormone use and the risk of ductal cancers increased 75%. The longer a woman took hormones the more her risk of ductal cancer increased -- doubling at about ten years, while lobular cancers were doubled within the first five 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 'safe' period is only two years. As in the other study, the risk disappeared within two years of stopping the drugs. The use of estrogen alone also increases breast cancer risk, but only 50% after ten years.



Once again it is clear that there is no such thing as a free lunch. Menopause is programmed in because we need it. We need high levels of hormones to reproduce the race and then shift down to a safer level with menopause. Artificially maintaining higher levels is not good for our health.