Report: As HRT use drops, breast cancer incidence declines

Analysis of declining breast cancer rates has strengthened a believed relationship between hormone replacement therapy (HRT) and incidence of the disease, according to a report in The New England Journal of Medicine. The research was performed by scientists at The University of Texas M.D. Anderson Cancer Center
Use of HRT in mid-2002 fell considerably, and this correlated with a considerable drop in new breast cancer cases throughout 2003, with a similar rate of incidence in 2004. The drop in cases was seen largely in women aged 50-69, and especially involving estrogen-receptor(ER)-positive cancer.
"For our new data set, 2004, the drop in breast cancer incidence leveled off and remained low in that year, showing that the decrease rates seen in 2003 were also present in 2004, meaning that the decline was not a one-year wonder, a short-lived anomaly," said M.D. Anderson's Peter Ravdin MD, PhD, professor in the department of biostatistics..
"This kind of study can't prove causality, but the data present a very compelling link between hormone replacement therapy and breast cancer," said Donald Berry, PhD, the study’s senior investigator, and head of the Division of Quantitative Sciences.
Ravdin and Berry make clear that their study is not suggesting that all women stop their use of HRT. "This study is not saying that an individual woman will reduce her absolute risk of developing breast cancer by 15 percent by immediately discontinuing use of HRT," Berry said. "At best, based on this analysis, an individual woman could reduce her individual risk of developing breast cancer by one in 60, or about 1.7 percent, if she stopped using hormones."