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2 Studies Look at Racial/Ethnic Disparities in Survival after Breast Cancer

Disparities in survival after breast cancer persisted across racial/ethnic groups even after researchers adjusted for multiple demographics, such as patients’ education and the socioeconomic status of the neighborhood in which they lived. 

These racial and ethnic disparities in breast tumor aggressiveness might be explained by social factors that influence the developing tumor and place those in disadvantaged groups at higher risk for aggressive breast cancer, according to data presented at the Fifth AACR Conference on The Science of Cancer Health Disparities, held Oct. 27-30, 2012.

In the first study on the disparities existing after being adjusted for multiple demographics, Salma Shariff-Marco, Ph.D., M.P.H., a researcher at the Cancer Prevention Institute of California in Fremont, said, “We learned that the effects of neighborhood socioeconomic status differed by racial/ethnic group. When simultaneously accounting for race/ethnicity and socioeconomic status, we found persistent differences in survival within and across racial/ethnic groups.”

Shariff-Marco and colleagues studied data from 4,405 patients with breast cancer who had participated in one of two population-based studies undertaken in the San Francisco Bay Area. Participants included 1,068 non-Latina whites, 1,670 Latinas, 993 African-Americans and 674 Asian-Americans.

All-cause survival was worse for African-Americans and better for Latinas and Asian-Americans compared with non-Latina whites after adjusting for age, study and tumor characteristics. When the researchers additionally adjusted for treatment and reproductive and lifestyle factors, they found that African-Americans had similar survival rates to non-Latina whites, but the survival rates of Latinas and Asian-Americans remained better.

Researchers also evaluated disparities in survival while considering racial/ethnic and socioeconomic status interactions. Compared with non-Latina whites with high education and high neighborhood socioeconomic status, worse survival was seen for African-Americans with low neighborhood socioeconomic status (regardless of education) and better survival was seen among Latinas with high neighborhood socioeconomic status (regardless of education) and Asian-Americans with high education and high neighborhood socioeconomic status.

The researchers noted that certain groups who were identified as having better or worse survival would benefit from further study to understand their risk profiles and target specific interventions.

“Understanding and addressing potential barriers to better survival are needed for groups with worse survival,” Shariff-Marco said. “One program that may be useful is patient navigation to ensure that these women are able to access and navigate the health care system. Sharing these findings with the broader public health community (e.g., health educators, community-based organizations and leaders) will also be helpful.”

In a second study that looked at whether social factors might be an issue, Garth H. Rauscher, Ph.D., associate professor of epidemiology at the University of Illinois at Chicago, said, “There is a disparity in the biological aggressiveness of breast cancer. We tend to think about biological differences being due to differences in genes, but tumor biology can be affected by social or behavioral factors that are associated with socioeconomic status. Our study highlights the importance of the social environment in influencing tumor biology and ultimately influencing disparities.”

Rauscher and colleagues examined data from a population-based sample of 989 patients with a recent diagnosis of breast cancer (397 non-Hispanic whites, 411 non-Hispanic blacks and 181 Hispanics) from the Breast Cancer Care in Chicago Study. Patients were aged 30 to 79 years and had primary in situ or invasive breast cancer. A total of 742 patients consented to medical record abstraction and had medical record data available for estrogen receptor (ER) and progesterone receptor (PR) status.

Researchers established socioeconomic disadvantage using four measurements: individual income, individual education and two census tract measures of socioeconomic status — concentrated disadvantage and concentrated affluence.

Compared with 12 percent of non-Hispanic white patients, 29 percent of non-Hispanic black patients and 20 percent of Hispanic patients had ER- and PR-negative tumors. Non-Hispanic black and Hispanic patients were also more likely to have lower income and less education and to reside in more disadvantaged and less affluent neighborhoods. In addition, all four measures of socioeconomic disadvantage used in the study were strongly associated with ER/PR-negative status.

“It was interesting to see that the main finding remained unchanged regardless of the measure of socioeconomic status we used,” Rauscher said. “Patient levels of income and education, as well as neighborhood-level measures of socioeconomic status, were each associated with tumor biology. In each instance, lower socioeconomic status was associated with more aggressive breast cancers that lacked these hormone receptors.”


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