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Survival has improved over time for white women with advanced breast cancer but not for their African American counterparts, according to one study. Results from a second review indicate African American women also may miss out on beneficial therapies.
Researchers analyzed the outcomes of 15,438 women who were newly diagnosed with stage IV cancers between 1988 and 2003 and included in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry. Patients were placed in one of three groups according to year of diagnosis. Their median age was 62 years.
Overall, survival improved over time from 16 months for women diagnosed in 1988-1993 to 20 months for women diagnosed in 1999-2003. The absolute improvement in survival was 3.7%, reported Dr. Sharon Giordano, one of the investigators from the M.D. Anderson Cancer Center at the University of Texas, Houston.
Median breast cancer-specific rates of survival also improved from 20 months in 1988-1993 to 25 months in 1999-2003.
When outcomes were compared by race, however, median breast cancer survival times improved for whites but not for blacks. Survival increased from 20 months for white women diagnosed in 1988-1993 to 27 months in 1999-2003. For black women, median survival was 17 months in 1988-1993 and remained at 17 months in 1999-2003.
The investigators could only speculate on the causes of the survival disparities in the epidemiologic study. Likely factors could include differences in access to care and more aggressive tumors contributing to poorer outcomes in black women. The SEER database does not include human epidermal growth factor receptor-2 (HER2) status, prohibiting an evaluation of its role in variations in survival by ethnicity.
If black women were less likely to have HER2-positive or estrogen receptor-positive disease, they wouldn't benefit from new drugs that specifically target those tumors. "That would be the most reassuring explanation of the difference," Dr. Giordano said.
A separate retrospective study indicated that the prevalence of stage III breast cancer is higher among African American women than among women of other ethnicities. Further, a considerable proportion of African American women in that study refused adjuvant and neoadjuvant therapy.
Dr. Monica Rizzo, of Emory University, Atlanta, and her associates reviewed the cases of 684 women with primary invasive breast cancers diagnosed or treated in 2000-2005. The women were seen at an inner city cancer center serving a population that was about 48% African American.
About 6%-7% of invasive breast cancers diagnosed in the United States are stage III, according to Dr. Rizzo, but 14% (96 cases) of the cancers in this series were stage III and 86% (83 of 96 cases) were in African American women.
Of the 96 cancers, 45 were stage IIIA, 33 were stage IIIB, and 12 were inflammatory breast cancers. Six stage IIIC cases were excluded from analysis.
Most patients got appropriate treatment, Dr. Rizzo said. In all, 88 of 90 patients received surgery and 2 refused. All with primary or residual tumors larger than 5 cm or with three or more axillary nodes were considered for chest wall and axillary radiation. In all, 48 of 74 patients received radiation therapy.
"Unfortunately, 21% of them refused chemotherapy and 35% refused radiation therapy," Dr. Rizzo said. The reasons for refusal need to be investigated.
It's vital to "adequately emphasize the importance of socioeconomic disadvantages and disparities" that likely contribute to differences in outcomes in African American women, said ASCO discussant Dr. Lisa Newman, of the University of Michigan, Ann Arbor.
Dawood S.S. et al. Trends in survival of stage IV breast cancer (BC) among Caucasian and African American (AA) BC patients (pts). Abstract 1000.
Rizzo M. et al. Differences in treatment in stage III breast cancer in African American women. Abstract 504.
Commentary |
The discordance in outcomes between white and African American populations with breast cancer has prompted a great deal of investigation and speculation. These two reports illustrate apparent differences between these populations with either stage III or IV disease. The study by Dawood et al. implies that the biology of the disease may be different, with African American patients potentially having more advanced disease with more aggressive characteristics. This is speculation, however, and not confirmed by the data presented. Perhaps more frustrating is the report by Rizzo et al. It suggests African American women with stage III disease may forgo optimal multimodality therapy shown to improve outcomes for women with locally advanced disease. What is not clear is the underlying reason or reasons behind the decision to decline treatments. More work on this issue will be critical to closing the gap between those women who live in poverty, are underinsured, or are uninsured and those who are positioned to receive optimum care. — William J. Gradishar, M.D.
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