Dr. Ravdin et al published a very impressive article in this week's New England Journal of Medicine on hormone replacement therapy (HRT) use and breast cancer rates.
They showed that the incidence (number of new cases) of breast cancer decreased in women who were 50 years of age or older from 2002 through the end of 2004. They tie this to the decrease in postmenopausal hormone replacement therapy and note that the decrease was largely in the number of new cases of restrogen receptor positive tumors.
The data on hormone replacement therapy and its relation to an increased incidence of breast cancer has been well publicized, although my latest take on the most recent iteration was that use for several years after menopause did not really increase the risk of breast cancer – that the increase was in women who had used hormone replacement therapy for 10 years or longer.
The hormone replacement therapy study is an interesting article and well thought out, and the authors are all highly respected doctors and statisticians from my alma mater, the National Cancer Institute. I must say though that I am not 100 percent convinced of cause and effect after reading the article. Tara Paker-Pope's column in the Wall Street Journal (4/19, page D3) highlighted some of the reasons behind this.
Is what's observed a slowing or delaying of tumors that will ultimately show up later? Are there other explanations such as a decrease in mammograms by women who stopped hormone replacement therapy? And last, is the amount of decrease concordant with what is seen -- stopping hormonal therapy should only reduce a woman's chance of developing breast cancer by 1.7 percent.
Probably long-term follow up of the same data set will provide more answers. Irrespective of the true cause and effect behind the trend, any decrease in the incidence of breast cancer is great news.
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