Posted online April 2, 2007, on www.jco.org 
A new study shows that recent declines in breast cancer death rates have been most significant among women with estrogen receptor (ER)-positive tumors and women younger than 70. The results of the study are being published online April 2 in the Journal of Clinical Oncology (JCO).
Between 1990 and 2003, breast cancer death rates declined by 24%. This is the first study to examine which patients have seen the greatest declines. In 1989, the death rate for breast cancer peaked at 33 out of 100,000 women per year. By 2003, the death rate had dropped to 25 out of 100,000 women per year.
Although death rates declined for all groups of patients, the declines were greatest for women under 70 and women whose tumors were ER-positive. The authors speculate that there are two factors primarily responsible for the greater decline in death rates for women with ER-positive breast cancer: the use of tamoxifen after surgery, which substantially reduces the risk of having the cancer come back in ER-positive tumors only,and the widespread use of mammograms, which may be more likely to detect the slow-growing tumors that tend to be ER-positive.
What Does This Mean for Patients?
Women of all ages – and women over 70 in particular – with breast cancer should be sure to discuss all possible treatment options with their doctors. While the study did not look at the reasons that breast cancer death rates went down less in older women, previous studies suggest that older women may be less likely to receive treatment after surgery for breast cancer. Because older women are under-represented in clinical trials, the best course of treatment for women over 70 has not yet been established. In addition, while it is too early to see the effects of newer breast cancer drugs on death rates, doctors believe some of them may have greater benefits for women with ER-negative tumors.