Abstract B083: Association of socioeconomic deprivation with breast cancer incidence, survival and ipsilateral recurrence by molecular subtype in Scotland, United Kingdom
Authors: Mesa-Eguiagaray Ines , Dunlop Hayley , Wild Sarah , Bird Sheila M. , Williams Linda , Hall Peter S. , Figueroa Jonine D. 
Published: December 2023

Abstract
Cancer disparities reflect the interplay of biological, environmental, and socioeconomic determinants. In the United States, disentangling racial and ethnic disparities in breast cancer (BC) including the effects of health care access and socioeconomic deprivation is challenging, given the latter highly correlated with race and ethnicity. In Scotland, United Kingdom (UK), the population is 96% White and there is a single payer National Health Service (NHS). The Scottish Index of Multiple Deprivation (SIMD) measures the extent to which a geographic area is deprived across seven domains: income, employment, education, health, access to services, crime and housing. Scotland is renowned for high-quality electronic health records including breast tumor estrogen receptor (ER) status collected since 1997 and Progesterone Receptor and HER2 since 2009, which can be linked to hospital data and mortality. To gain a better understanding of individual patients’ SIMD status (measured in quintiles) at BC diagnosis with incidence and survival, we used data on 62,378 women diagnosed with invasive BC between 2000 and 2016. For ipsilateral breast recurrence (IBR) outcomes, we used a subset of data for BC diagnosed 2007-2008 where manual case-note review was performed for 3495 patients from 10 years post-diagnosis. Screen-detected ER+ tumor incidence increased over time, particularly in the least deprived quintile [Average Annual Percentage Change = 2.9% with 95% CI from 1.2 to 4.7]. No marked differences were observed for non-screen-detected ER+ tumors or ER- tumors by SIMD. Most versus least deprived SIMD-quintile was associated with significantly higher mortality for luminal A and HER2-enriched tumors in multivariable Cox proportional hazard models adjusted for mode of detection and confounders (aHR = 1.46 [1.13, 1.88] and 2.10 [1.23, 3.59] respectively) but weaker non-significant associations for luminal B and triple negative BC tumors (aHR &lt;1.20). Among 2,819 ER+ tumors, 423 patients had IBR (15%) and 438 died: SIMD was related to death (p=0.018) with the most deprived more likely to have died in the first decade of follow-up (17.7% vs 12.9%). We found no significant differences by SIMD in prognostic tumor characteristics (grade, TNM stage, treatment, screen-detection) or risk of IBR. Among 676 patients diagnosed with ER- tumors, 185 had IBR (27%) and 105 died: 50% had mastectomy and the most deprived had an increased 5-year IBR risk compared to the least deprived (aHR 3.03 [1.41-6.53]). Our analysis shows socioeconomic deprivation is associated with differential BC incidence trends for screen-detected ER+ tumors and higher mortality and IBR for selected tumor subtypes. The lack of inequities for triple negative tumors by SIMD and survival, and IBR for ER+ tumors may be due to standardized treatment protocols and healthcare access. The association with socioeconomic deprivation and survival for HER2+ and recurrence among ER- tumors requires further study on potential other factors such as co-morbidities and adherence to treatment.
Citation Format: Ines Mesa-Eguiagaray, Hayley Dunlop, Sarah Wild, Sheila M. Bird, Linda Williams, Peter S. Hall, Jonine D. Figueroa. Association of socioeconomic deprivation with breast cancer incidence, survival and ipsilateral recurrence by molecular subtype in Scotland, United Kingdom [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr B083.