The study, led by M. Catherine Lee, a clinical lecturer at the University of Michigan Comprehensive Cancer Center's department of surgery, is the largest to indicate a biological factor as the cause of black women's increased mortality from the disease, according to the Newark Star-Ledger. Previous research has attributed fewer mammograms and less aggressive treatment to the racial disparity (Stewart, Newark Star-Ledger, 9/6). Black women are less likely than white women to develop breast cancer but are more likely to die from the disease.
For the study, Lee and colleagues analyzed data on more than 170,000 breast cancer diagnoses from 1998 that were included in the American College of Surgeons' National Cancer Data Base. Ten percent of the cases were among black women.
Researchers focused on 95,500 women whose cancers were invasive rather than confined to a milk duct. They found that roughly 39% of such tumors in black women were estrogen receptor-negative, or ER-negative, compared with 22% of tumors in white women.
ER-negative tumors are resistant to common hormone-based therapies like tamoxifen and are more difficult to treat, according to the AP/Times (AP/Los Angeles Times, 9/5). The high prevalence of ER-negative tumors among black women was consistent regardless of the age or stage at which they were diagnosed, the study found (Newark Star-Ledger, 9/6).
The study also found that black women were diagnosed at an average age of 57, compared with 62 for white women. Black women's tumors also were more advanced than white women's, with 29% of black women having stage 1 tumors that had not yet spread, compared with 42% of white women.
Lee said, "Differences in tumor biology have a significant impact on survival," adding, "The fact that breast cancers in black women are more aggressive biologically suggests that we need to focus more of our research energy on developing better treatments targeting ER-negative tumors." She said the "findings also point to a need for improved cancer education and screening in black women, particularly those in younger age groups".
Source: Kaiser Family Foundation