Background:Breast cancer outcomes in minority and low socioeconomic status populations are not clearly defined due to underrepresentation of these underserved populations in breast cancer clinical trials and population-based studies. The Southern Community Cohort Study (SCCS), a prospective cohort of underserved, predominantly Black participants, provides a unique opportunity to evaluate disparities in breast cancer outcomes. We sought to examine the association between race and socioeconomic status (SES) and overall survival (OS) in women with localized breast cancer in the SCCS.

Methods:The SCCS enrolled approximately 86,000 participants aged 40-79 from 12 Southeastern states between 2002-2009, 86% of whom were enrolled at Community Health Centers. This analysis includes women diagnosed with incident localized breast cancer (stage I-III) identified through annual cohort linkage with 12 state cancer registries through December 20, 2017. Demographic data including participant age, self-reported history of diagnosed diabetes, body mass index (BMI), race, annual household income, and insurance coverage were obtained from baseline surveys. Tumor grade and stage were obtained from state cancer registries, and survival data were obtained from death registry records. Immunohistochemical (IHC) subtype was determined from tumor estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) status obtained from cancer registry records and pathology reports. Survival time was defined as the number of months between initial breast cancer diagnosis and death from any cause. Descriptive analyses including mean (standard deviation) and number (%) were used to summarize clinical and sociodemographic characteristics by race. Multivariable Cox survival analysis was used to evaluate OS by race and annual household income, adjusting for age, insurance, stage, IHC subtype, diabetes, and BMI.

Results:Of the 1347 women diagnosed with incident breast cancer, 1016 had localized disease (stage I-III) and comprised our analytic sample. Compared to White women, Black women were more likely to have lower income, higher prevalence of triple negative breast cancer (TNBC), grade III tumors and stage III breast cancer (Table 1). After adjusting for clinical and sociodemographic factors, Black women had similar OS compared to White women (HR 0.67; 95% CI 0.42-1.07). However, after adjusting for race, women with a household income ≥ $25,000 had an improved OS compared to those with annual household income < $25,000 (HR 0.53; 95% CI 0.30-0.93).

Conclusion:In a low-income, medically underserved population, Black women with localized breast cancer had similar OS compared to White women. However, socioeconomic disparities were observed, with worse OS for women with low annual household income. Future studies focused on minority, underserved groups are imperative to better understand the non-biological and biological factors contributing to disparities in survival among women with breast cancer.

Table 1. Patient characteristics overall and by race

Patient CharacteristicsTotal(N=1016)Black(N=667)White(N=349)P-value*
Age at diagnosis, years (Mean, SD) 61 (9) 60 (9) 63 (9)  
Income, annual household (N, %) < $25,000 ≥ $25,000 719 (71)297 (29) 503 (75)164 (25) 216(62)133 (38) <0.001 
Insurance (N, %) Private insurance Medicare Medicaid Uninsured 220 (29)331 (43)178 (23)34 (5) 152 (29)209 (40)139 (26)26 (5) 68 (29)122 (51)39 (16)8 (3) 0.005 
Diabetes (N, %) No history of diabetes History of diabetes 736 (74)258 (26) 469 (72)183 (28) 267 (78)75 (22) 0.04 
BMI, kg/m2 (N, %) 18.5-30.0 kg/m2 30.0+ kg/\\ 411 (40)605 (60) 239 (36)428 (64) 172 (49)177 (51) <0.001 
IHC subtype (N, %) HR+,HER2- HR+,HER2+ HR-,HER2- TNBC 392 (69)55 (10)34 (6)86 (15) 255 (65)38 (10)26 (7)75 (19) 137 (79)17 (10)8 (5)11 (6) 0.001 
Grade (N, %) I II III 188 (20)383 (41)372 (39) 111 (18)239 (38)277 (44) 77 (24)144 (46)95 (30) <0.001 
Stage (N, %) I II III 460 (45)383 (38)173 (17) 278 (42)261 (39)128 (19) 182 (52)122 (35)45 (13) 0.003 
Patient CharacteristicsTotal(N=1016)Black(N=667)White(N=349)P-value*
Age at diagnosis, years (Mean, SD) 61 (9) 60 (9) 63 (9)  
Income, annual household (N, %) < $25,000 ≥ $25,000 719 (71)297 (29) 503 (75)164 (25) 216(62)133 (38) <0.001 
Insurance (N, %) Private insurance Medicare Medicaid Uninsured 220 (29)331 (43)178 (23)34 (5) 152 (29)209 (40)139 (26)26 (5) 68 (29)122 (51)39 (16)8 (3) 0.005 
Diabetes (N, %) No history of diabetes History of diabetes 736 (74)258 (26) 469 (72)183 (28) 267 (78)75 (22) 0.04 
BMI, kg/m2 (N, %) 18.5-30.0 kg/m2 30.0+ kg/\\ 411 (40)605 (60) 239 (36)428 (64) 172 (49)177 (51) <0.001 
IHC subtype (N, %) HR+,HER2- HR+,HER2+ HR-,HER2- TNBC 392 (69)55 (10)34 (6)86 (15) 255 (65)38 (10)26 (7)75 (19) 137 (79)17 (10)8 (5)11 (6) 0.001 
Grade (N, %) I II III 188 (20)383 (41)372 (39) 111 (18)239 (38)277 (44) 77 (24)144 (46)95 (30) <0.001 
Stage (N, %) I II III 460 (45)383 (38)173 (17) 278 (42)261 (39)128 (19) 182 (52)122 (35)45 (13) 0.003 

HR = Estrogen receptor (ER) and/or progesterone receptor (PR)* denotes p-value for White compared Black women

Citation Format: Sonya Reid, Lucy B Spalluto, Diane Haddad, Tuya Pal, Ingrid Mayer, Xiao-ou Shu, Wei Zheng, Maureen Sanderson, William Blot, Loren Lipworth. The association of race and socioeconomic status with overall survival in women with breast cancer in the southern community cohort study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS7-34.