BETHESDA, MarylandA new study shows that recent declines in breast cancer mortality rates have been most significant among women with estrogen-receptor (ER)-positive tumors and women younger than age 70 (J Clin Oncol published online April 2, 2007). Between 1990 and 2003, breast cancer mortality rates declined by 24%. The researchers found that among women under age 70, mortality declined 38% for those with ER-positive tumors vs 19% for ER-negative tumors, and among women 70 or older, by 14% for ER-positive tumors vs no decline for ER-negative tumors.
"These trends since 1990 are likely attributable to at least two factors: the use of tamoxifen after surgery . . . and widespread use of screening mammography, which is more likely to detect the slow-growing tumors that tend to be ER-positive," said lead author Ismail Jatoi, MD, PhD, of the Uniformed Services University of the Health Sciences.