Black women in the United States are more likely than white women to have a subtype of breast cancer, called estrogen receptor (ER)-negative, that is more aggressive and more difficult to treat, according to a large study from the University of Michigan. ER-negative cancers tend to grow faster and are harder to treat because hormone therapy, such as tamoxifen (Nolvadex), is not effective for these cancers.

Although white women are more likely to develop breast cancer than black women, black women are more likely to die from breast cancer. Also, black women tend to be diagnosed with breast cancer at younger ages and at later stages of disease than white women. These differences are usually attributed to socioeconomic factors, such as access to screening and adequate cancer care, but this analysis suggests that the biology of breast cancer may also be involved.

In this study, researchers analyzed data on 170,079 cases of breast cancer included in the National Cancer Data Base (NCDB), a multi-institutional tumor registry that collects cancer data from 1,600 hospitals in all 50 states. Black women made up 10% of these records; white women accounted for 90% of the records. Of the women with invasive cancer, ER-negative cancer was identified in 39% of black women, compared with 22% of white women. In addition, black women were diagnosed at a younger age (57) than white women (62). Fewer black women (29%) were diagnosed at an early stage (stage I) than white women (42%), and black women also had larger tumors at diagnosis, two factors that can lower breast cancer survival.

What This Means for Patients

"Differences in tumor biology affect survival," said M. Catherine Lee, MD, Clinical Lecturer in the Department of Surgery at the University of Michigan Comprehensive Cancer Center in Ann Arbor. "The fact that breast cancers in black women are more biologically aggressive suggests that we need to focus more of our research energy on developing better treatments for ER-negative tumors. These findings also point to a need for improved cancer education and screening in black women, particularly those in younger age groups."