Association of community-level deprivation with breast cancer risk and survival among women residing in the southeastern United States

Background Studies on the association of community-level deprivation indices with breast cancer risk and survival after breast cancer diagnosis have yielded mixed results, and few have included large enough samples of low-income and ethnic minority individuals and considered individual-level risk factors. Methods This study included 43,384 cancer-free female participants enrolled from 2002-2009 in the Southern Community Cohort Study (SCCS), a prospective cohort study of predominantly low- income individuals and followed through December 2019 to ascertain incident breast cancer and survival outcomes. In-person or mailed baseline surveys collected information on demographic, reproductive and lifestyle factors. Neighbourhood deprivation index (NDI) was estimated based on participants’ residential zip codes and the 2000 census tract data. We conducted multivariable Cox regression analyses to evaluate the association of NDI with the risk of developing breast cancer and breast cancer-specific survival while adjusting for confounding effects of reproductive, lifestyle, clinical, and individual-level socioeconomic factors. Results Approximately 69% of participants were Black, 31% were white, and 78% had family income < $25,000/year. After a median follow-up of 12.8 years, 1,363 women were diagnosed with incident breast cancer (median age at diagnosis of 54.0 (IQR 13.0) years); 365 of them died, and 218 died from breast cancer. White women living in the least deprived communities had a significantly increased risk of developing breast cancer but not dying from breast cancer, with a hazard ratio (HR) of 1.44 (95% confidence interval (CI) 1.05-1.96) and 1.11 (95% CI; 0.48- 2.59), respectively. Among Black women, NDI was not associated with breast cancer risk or survival. Conclusion This large cohort of Black and white women with predominantly low-income background found no evidence that living in a deprived neighbourhood further increases the incidence and mortality of breast cancer.