A special report in the April 19 issue of the New England Journal of Medicine [1] brings initial analysis of data from the National Cancer Institute's Surveillance, Epidemiology and End Result (SEER) registries, showing that the incidence of breast cancer in women in the US fell by 6.7% in 2003, and stayed at the same level in 2004.
The decrease was evident only in women who were 50 years of age or older, and solely involved cancers that were estrogen receptor-positive. The investigators suggested that a plausible explanation for the unexpected data is the concomitant sharp decrease in the use of postmenopausal hormones, which followed the first report from the Women's Health Initiative (WHI) study in mid-2002.
While being pleased with these new data on the incidence of breast cancer, the International Menopause Society (IMS) advises caution in linking these two parallel trends observed in the US. Any attempt to put both observations into one framework is premature and there is little scientific basis for such an assumption. In fact, the authors themselves mention in the manuscript that other factors might have contributed to these changes in breast cancer incidence. Nevertheless, the reader of the article still receives a clear message on the presumed association with hormone therapy (HT).
The IMS wishes to stress the following relevant facts: