Kerlikowske K, Miglioretti DL, Buist DS, et al. Declines in invasive breast cancer and use of postmenopausal hormone therapy in a screening mammography population. J Natl Cancer Inst. 2007 Sep 5; 99(17):1335-1339.
New research indicates that the recent U.S. drop in breast cancers may be more the result of declining use of hormone therapy and not due to a drop in mammography-linked detection.
The authors claim that the study is the only one of its kind that has looked at a purely screened population, and the results definitely indicate the decline is not because of screening. In 2002, the results of the Women's Health Initiative found elevated health risks, including breast cancer, among women who were taking a combination of estrogen and progestin. Declines in breast cancer were seen shortly after these results were released.
There are studies that have indicated a decline in screening mammography is responsible, but others also find hormone therapy to be the reason. This recent study reviewed over 600,000 mammograms performed between 1997 and 2003 on women ages 50 to 69 years. Hormone therapy use declined by 7% a year between 2000 and 2002, then by 34% between 2002 and 2003. During this same period, breast cancer rates declined annually by 5% and estrogen-receptor-positive breast cancer rates fell by 13% annually from 2001 to 2003.
The authors suggest that women should consider taking hormone therapy for the least amount of time possible to relieve menopausal symptoms.