UC DAVIS (US) — Black women are 50 percent more likely than any other racial or ethnic group to die from advanced breast cancer, even if they receive radiation therapy.
“We knew from our earlier study that blacks with advanced breast cancer were less likely to be treated with radiation, so we expected to see that their survival would be poorer because of that,” says Steve R. Martinez, assistant professor of surgical oncology at University of California, Davis.
“We were surprised to find that blacks fare worse regardless of whether they receive radiation therapy and actually appear to be less responsive to one of our most important treatments.”
The study, published online in the journal Cancer, evaluated data from more than 12,000 patients in the Surveillance, Epidemiology and End Results database with advanced breast cancer between 1988 to 2005.
The data allowed analysis of patients by racial and ethnic group, types and characteristics of breast cancer, type of surgery, and whether or not they received radiation therapy.
A previous study from Martinez showed that blacks are not as likely as whites and Asians to receive radiation therapy following breast cancer surgery.
The new findings, however, indicate that lack of radiation therapy was not a factor in the higher death rates and raises questions regarding what actually causes the poorer survival.
Although in the earlier study, Hispanic patients, like blacks, were found to be less likely to receive radiation therapy, the new research shows that their survival rates were similar to those of whites and Asians. The reason Hispanics actually did better than expected is also unknown.
In general, radiation therapy is recommended for all patients with breast cancer who undergo lumpectomy (removal of only the tumor and the surrounding tissue) as well as for those who have mastectomy (complete breast removal) if the tumor is large or at least four lymph nodes are also found to be cancerous.
Patients with advanced breast cancer typically also are treated with hormonal or chemotherapy before or after surgery.
“Why blacks fare worse from breast cancer is the million-dollar question,” says Martinez. “This study is significant in the questions it raises, and looking for the answers is critical as we go forward.”
One explanation for the disparity may be that blacks have a biologically different form of breast cancer that is more aggressive and less responsive to radiation and other therapies.
Blacks also may be more often predisposed to life-threatening complications of radiation therapy such as stroke, cardiac disease and lung damage.
It has also been shown in other studies that blacks are less likely than whites to receive chemotherapy or hormonal therapy, which could account for the higher death rates.
Information about the use of hormonal and chemotherapy is not as accessible from current databases as information about radiation therapy, Martinez says, but because there are several causes of health-care disparities, studying and better understanding them are crucial to improve the care provided to all patients.
“Disparities may be due to poor access to care, in which case research in these areas can help focus health-care dollars to target particular populations in need,” he says.
“Disparities in cancer survival may also be the result of differential tumor biology among populations. Identifying these biological differences may help us find more specific, individualized and targeted therapies for treatment.”
The research was supported by the National Institutes of Health.
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