Despite modest overall improvements in breast cancer survival rates for women with advanced disease over the last two decades, the rates for black women have not improved and the difference in life expectancy between white and black women continues to widen, according to researchers at The University of Texas M. D. Anderson Cancer Center.
The study, presented June 3 at the 43rd annual American Society of Clinical Oncology (ASCO), is the first to show that improvements in breast cancer survival only benefit white women and that the disparity between black and white breast cancer patients is widening.
The study evolved as a follow-up to recent research of Sharon Giordano, M.D., assistant professor in M. D. Anderson's Department of Breast Medical Oncology, that found an overall improvement in the survival of Stage IV breast cancer patients enrolled in clinical trials at M. D. Anderson.
"We wanted to expand our research and look to a bigger subset of patients treated in the community to see if we would find similar results," says Shaheena Dawood, M.D., a Susan G. Komen Fellow in Breast Medical Oncology at M. D. Anderson. "We thought we would find that there was improvement in women with Stage IV breast cancer regardless if patients were white or black, with white women likely having better outcomes. Rather, over the decades, we found that black women's survival did not improve at all."
The researchers analyzed the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) database to identify 15,438 women who were newly diagnosed with advanced breast cancer between 1988 and 2003. Adjustment factors included: patient age; estrogen receptor status; and tumor grade.
Patients were divided into three subgroups: those diagnosed from1988 to 1993; from 1994 to 1998; and from 1999 to 2003. Overall, the median age of the women was 62 years old; median breast cancer-specific survival was 20 months, 21 months and 25 months respectively.
In those diagnosed with advanced breast cancer between 1988 and 1993, the median survival was 20 months in white women, compared to 17 months for black women, a one-year survival difference of 2.8 percent. In the women diagnosed between 1994 and 1998, a white breast cancer patient's median survival was 22 months versus 16 months in black patients, a one-year survival difference of 6.8 percent. In those diagnosed from 1999 to 2003, the median survival for white women was 27 months compared to 17 months for black women, a one-year survivor difference of 8.8 percent.
"We do not suspect that these statistics are due to the biology of the disease because we would not expect the biology to change over time. It's more likely due to socio-economic factors," says Giordano, the study's senior author. "While SEER data does not code for treatment, we hypothesize that lack of access to healthcare and to newer modalities for treatment of Stage IV breast cancer, such as targeted therapies like Herceptin and aromotase inhibitors, are two contributing factors for the growing disparity."
In 2007, more than 180,510 women will be diagnosed with breast cancer and approximately 40,910 women are expected to die from the disease, according to the American Cancer Society. Of the new cases of breast cancer, the researchers say that 10 percent of the patients are diagnosed with metastatic breast cancer and that mortality rates for women with advanced breast disease are decreasing by 2.3 percent annually.
The researchers hope that health policy makers take notice of the growing disparity and implement steps to make all breast cancer treatments more accessible. Giordano and Dawood also intend to expand upon their research and determine the causation of these racial disparities.
Dr. Giordano is supported by NIH KO7 CA 109064-03.
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