Abstract B19: Understanding racial/ethnic and multilevel socioeconomic disparities in survival after breast cancer.
Authors: Shariff-Marco Salma , Yang Juan , Sangaramoorthy Meera , Hertz Andrew , John Esther M. , Koo Jocelyn , Nelson David O. , Schupp Clayton , Keegan Theresa H.M. , Gomez Scarlett Lin 
Published: August 2014

Background: Racial/ethnic disparities in survival after breast cancer persist, even after accounting for socioeconomic status (SES); however, few studies have evaluated both individual and neighborhood SES jointly. In particular, evaluating the interactions between multiple components of social status (e.g., race/ethnicity, SES, nativity) simultaneously may help us to better understand the survival disparities. Our hypothesis is that social status measures jointly influence health.

Methods: Our study included 4,405 breast cancer patients diagnosed in the period 1995-2008, representing non-Latina whites (n=1068), Latinas (n=1670), African Americans (n=993) and Asian Americans (n=674) from two population-based studies in the San Francisco Bay Area. Using stage-stratified Cox proportional hazards models, we assessed the association between race/ethnicity and all-cause and breast cancer-specific survival, after adjusting for education, neighborhood SES (nSES), and other prognostic factors (e.g., treatment, reproductive, and lifestyle factors). We also examined the interaction of 3 social status variables (race/ethnicity, education (low=≤HS graduation/high=≥ some college) and neighborhood SES (low=quintiles 1-3/high=quintiles 4-5)) on survival.

Results: All cause survival was worse for African Americans (HR=1.37, 95% CI=1.14-1.64) and better for Latinas (HR=0.77, 95% CI=0.64-0.92) and Asian Americans (HR=0.83, 95% CI=0.65-1.08) compared to non-Latina whites after adjusting for age, study, tumor characteristics. Additionally adjusting for treatment, reproductive and lifestyle factors attenuated associations for African Americans, such that they had similar survival to non-Latina whites, whereas the better survival observed among Latinas and Asian Americans remained. Social status disparities in survival after breast cancer were also evident in models considering the racial/ethnic and SES interactions. Compared to high education/high nSES non-Latina whites, all-cause survival was worse for low education/low nSES non-Latina whites, low nSES African Americans (regardless of education), and low education/low nSES Asian Americans, whereas all-cause survival was better for high nSES Latinas (regardless of education) and high education/high nSES Asian Americans. Accounting for additional prognostic factors attenuated associations for low education/low nSES Whites and low education/low nSES Asian Americans. Similar patterns were observed for breast cancer-specific survival.

Discussion: Racial/ethnic disparities in survival after breast cancer persisted after adjusting for education, neighborhood SES and other prognostic factors. Our findings of racial/ethnic disparities in survival are consistent with prior literature. When simultaneously accounting for multiple social statuses, we found that disparities existed within and across racial/ethnic groups. We were able to identify specific subgroups based on multiple dimensions of social status that are at increased and decreased risk of mortality (e.g., African Americans in low SES neighborhoods, Asians with low education and low nSES, and Latinas in high nSES). These subpopulations would benefit from further study to better understand their risk profiles and for targeting specific interventions.

Citation Format: Salma Shariff-Marco, Juan Yang, Meera Sangaramoorthy, Andrew Hertz, Esther M. John, Jocelyn Koo, David O. Nelson, Clayton Schupp, Theresa H.M. Keegan, Scarlett Lin Gomez. Understanding racial/ethnic and multilevel socioeconomic disparities in survival after breast cancer. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr B19.