Study results published in the Journal of the National Cancer Institute suggest that invasive breast cancer rates have fallen since the substantial decline in the use of postmenopausal hormone replacement therapy (HRT), according to Reuters Health.
The National Cancer Institute study sought to determine whether the recent drop in breast cancer was related to a decline in the use of hormone therapy or to a decline in screening mammography. The researchers collected data from four registries on more than 600,000 screening mammography examinations on women aged 50-69, which were conducted from 1997 to 2003. This information, calculated quarterly, was compared with trends in annual rates of breast cancer and postmenopausal HRT use.
The results of the analysis indicated that annual rates of postmenopausal HRT use declined between 2000 and 2003, which corresponded to the annual rates of invasive breast cancer. Between 2001 and 2003, annual rates of estrogen receptor–positive invasive breast cancer also declined.
Although breast cancer rates were not determined separately for patients who had formerly or never used HRT, the findings suggest that the U.S. decline in estrogen receptor–positive breast cancer is unlikely related to a decline in the screening mammography rate, and more likely linked to the decline in use of postmenopausal HRT.