Abstract PO1-09-10: County-level Social Vulnerability and Survival among Women with Inflammatory Breast Cancer

Abstract Purpose: Inflammatory breast cancer (IBC) is an aggressive form of breast cancer with a poor overall prognosis compared to other forms of breast cancer. Advances in treatment have contributed to improvement in IBC survival rates in recent years, yet disparities in outcomes persist. It is unclear whether social determinants of health impact IBC prognosis independent of access to quality cancer care. Thus, the aim of this study was to examine whether the US county-level social vulnerability index (SVI) was associated with IBC stage at diagnosis and overall survival (OS) among women with IBC treated at a single institution. Methods: Patients enrolled in the IBC registry at Dana-Farber Cancer Institute (DFCI) were included in this study. We linked participant’s residential zip codes to the 2020 CDC’s county-level SVI, which is calculated from 15 social determinants of health attributes from the American Community Survey including socioeconomic status, household composition, language and minority status, and housing and transportation factors. The SVI value reflects the percentile of counties in the nation that are less vulnerable than the county of interest. We assessed associations between SVI and stage at diagnosis using t-tests. Kaplan-Meier curves and log-rank tests were used to assess survival across SVI quartiles based on distribution (1st [least vulnerable] and 4th [most vulnerable]). Using hierarchical logistic regression models and Cox proportional hazards models with mixed effects incorporating cluster-specific random effects that modify the baseline hazard function, we assessed whether SVI is associated with the presence of de novo metastatic disease and OS in IBC. Results: A total of 586 women (86% White) enrolled in the IBC registry at DFCI between 1986 and 2021 were included in this study. Of these, 69.1% had stage III and 30.9% had de novo metastatic disease. 280 deaths occurred in the study population over a mean follow-up of 4.1 years. SVI for the counties where study participants resided ranged from 2.6% to 95.8% (median=34.2%). The mean SVI did not significantly differ according to stage at diagnosis (41.6% in non-metastatic and 40.8% in metastatic at presentation; p=0.70). OS did not significantly differ across SVI quartiles (p-value=0.63). In the age-adjusted models, the SVI was not associated with the presence of de novo metastatic disease (odds ratio (OR (95% CI)=0.99 (0.84, 1.16)) or OS (HR (95% CI)=0.79 (0.46, 1.33). Conclusions: Our findings that residing in socially vulnerable US counties is not associated with the presence of de novo metastatic disease or IBC survival among a subset of women accessing high-quality cancer care suggest that improving access to quality cancer care may overcome underlying socioeconomic factors that contribute to disparities in IBC outcomes. Future studies are needed to confirm these findings in other settings. Citation Format: Kelly Hirko, Elizabeth Troll, Sean Ryan, Faina Nakhlis, Jennifer Bellon, Olga Kantor, Christina Minami, Eren Yeh, Ilana Schlam, Laura Warren, Caroline Block, Susan Schumer, Filipa Lynce. County-level Social Vulnerability and Survival among Women with Inflammatory Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-09-10.