Racial differences in breast cancer survival rates have worsened since 1980, but the disparity cannot be attributed entirely to inequalities in the healthcare access, according to results of a study of women in the Department of Defense (DoD) healthcare system, published in the journal Cancer.
Today, African-American women with breast cancer are almost two times more likely to die than Caucasian women, marking a significant increase in risk compared to the early 1980s. This survival difference has worsened even in an equal access healthcare system, according to the new study.
The authors of the study conclude, "there is clearly a need to identify other factors responsible for the widening racial disparity in breast cancer outcomes." Possible factors include tumor biology, treatment and obesity.
Previous studies have shown a growing disparity in survival rates for breast cancer between African-Americans and Caucasians over the last 20 years. The cause of this disparity is uncertain and evidence does not identify a single factor. Some studies support the theory that inequality in access to physicians, screening mammograms and treatment explains the differences. Yet another string of evidence suggests that differences in the tumor itself or environmental and behavioral factors such as obesity influence tumor prognosis. However, no study to date has investigated trends in breast cancer survival in an equal access system.
The DoD healthcare system provides free and equal access to healthcare for all beneficiaries, making it an excellent control for the healthcare access factor. Jatoi et al. reviewed medical records in the DoD healthcare system from 23,612 women diagnosed and treated for primary breast cancer between 1980 and 1999.
The survival of African-American women compared to Caucasian women as measured by the hazard ratio showed an increasing risk of death between 1980 and 1999. In the period 1980-1984 African-American women with breast cancer were 1.3 times more likely to die than Caucasian women. In the 1995-1999 period, African-American women were 1.8 times more likely to die than Caucasian women.
Caucasians showed greater improvement in overall survival than African-Americans over the 20 years of this review. Moreover, there was a greater shift towards diagnosis at an earlier stage in Caucasians than African-Americans. There was no difference in surgical treatment though African-Americans were more likely to receive chemotherapy and Caucasians were more likely to receive hormone therapy, possibly reflecting the greater percentage of estrogen-negative tumors that do not respond to hormone therapy found in the African-American patients.
The authors summarize, "we do show that disparity in survival rates among Caucasians and African Americans has increased in the DoD healthcare system. These results suggest that the widening racial disparity in breast cancer outcomes in the United States cannot entirely be ascribed to inequalities in access to healthcare."
Cancer, September 1, 2003