Race Plays Part in Breast Cancer Survival

CancerWise - March 2007

African-American women with breast cancer often have tumors that are larger, in later stages and more difficult to treat than their Hispanic and Caucasian counterparts, according to a recent study.

Significance of results

The M. D. Anderson study shows that African-American women’s tumors often have biology that is less susceptible to treatment. Researchers say this combines with other factors to lower the rate of breast cancer survival among African-American women.

“Not all African-American women will have worse survival prospects, but there are probably subsets of patients for whom we could be doing something better,” says Wendy Woodward, M.D., Ph.D., assistant professor in M. D. Anderson’s Department of Radiation Oncology and first author of the study.

Research methods

This study examined tumors of 2,140 female breast cancer patients who were treated in two clinical trials at M. D. Anderson between 1975 and 2000. Both groups were treated with mastectomy and doxorubicin-based chemotherapy.

The women included:

• 1,590 Caucasians
• 300 Hispanics
• 250 African-Americans

The analysis took into account the:

• Woman’s age
• Estrogen receptor-negative status of tumor
• Primary tumor size
• Isolation of cancer or if it had spread to lymph nodes

Primary results

African-American women were more likely to have estrogen receptor-negative tumors, which are considered more difficult to treat.

Researchers say the study shows that, while socioeconomic factors probably play a part, race is an independent factor in the lower overall breast cancer survival rate of African-American women.

“We interpret these data as suggesting that intrinsic biological differences in the disease and response to treatment among racial groups contributed to the poorer overall survival rates seen in the African-American patients,” Woodward says.

Background

Although African-American women are less likely than Caucasian women to have breast cancer, they are more likely to die from the disease.

This disparity has been attributed to several possible factors, including:

• Access to health care and screening
• Body mass index
• Co-morbidities, such as diabetes and high blood pressure
• Differences in treatments
• Socioeconomic status
• Racial bias

However, in M. D. Anderson’s referral area Hispanic women have similar socioeconomic status, and they do not show lower breast cancer survival rates. Therefore, researchers discount the theory that socioeconomic factors completely explain differences.

Since this study was limited to patients treated in institutional clinical trials, researchers feel it minimized biases related to access to treatment and difference in treatment type. Of course, those issues may have been present before patients enrolled in the trials.

What’s next?

Although this study is inconclusive, it begs for more in-depth research on tumor types and outcomes in African-American women.

“These findings should prompt additional research on how we can improve outcomes for African-American patients by understanding and addressing tumor biology,” Woodward says.

M. D. Anderson resources:

• Breast cancer
• Radiation Treatment Center

Other resources:

• Breast cancer (American Cancer Society)
• African-American cancer burden (American Cancer Society)