Abstract PS4-09-03: Impact of comorbidities and race in breast cancer survival across cancer stages

Abstract Background: Breast cancer survival varies by race, influenced by factors like socioeconomic status, access to care, and comorbid conditions. While comorbidities independently worsen survival, their role in shaping racial differences across cancer stages is less clear. Emerging data suggest that racial disparities in survival may be masked when comorbidities are present and only become apparent among patients without other medical illnesses. Understanding how comorbidities and race interact, and whether removing the comorbidity burden reveals racial disparities, is crucial for addressing inequities and informing next steps, including evaluating the impact of socioeconomic factors on these disparities. Methods: We conducted a retrospective cohort study of breast cancer patients diagnosed between 2018 and 2023 using the N-Power Medicine database of cancer patients in the United States. We grouped patients as White/Asian (W/A) or Black/Other (B/O), combining Black, Native American, and Pacific Islander patients into the latter category, and compared their baseline demographics and comorbidity profiles using standard statistical methods. We used Cox regression and random forest models to analyze factors associated with all-cause mortality (ACM). Comorbidities analyzed included cardiovascular disease (CVD), diabetes (DM), chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), peripheral vascular disease (PVD), and chronic kidney disease (CKD). Additional analyses were performed, stratifying patients by cancer stage and the presence or absence of comorbidities, to evaluate racial differences in survival outcomes. Results: Among 31,150 patients (W/A = 26,136; B/O = 5,014), the median age was 61 and 62 years, respectively. B/O patients demonstrated higher ACM when controlling for comorbidities (HR 1.3 (1.2-1.4)). All comorbidities increased ACM in both racial groups as follows: CVD (HR 2.5 (1.6, 3.9)), DM (HR 1.6 (1.2, 2.0)), COPD (HR 1.5 (1.0, 2.1)), CHF (HR 2.5 (1.8, 3.7)), PVD (HR 2.3 (1.6, 2.4)), CKD (HR 2.6 (2.0, 3.3)). The most significant comorbidities for predicting ACM were CKD and CHF. We did not identify a significant interaction between comorbidities and race, specifically: CVD (p = 0.665), DM (p = 0.665), COPD (p = 0.06), CHF (p = 0.06), PVD (p = 0.373), and CKD (p = 0.844). Stage-stratified analysis revealed significant racial disparities in survival only among patients without comorbidities, with B/O patients exhibiting higher mortality compared to W/A patients across stages I-IV (HR range 1.2-1.6). This racial difference was notably absent among patients with comorbidities. Conclusion: Among breast cancer patients, comorbidities and race each independently increased ACM. However, racial differences in survival emerged only among patients without comorbidities, suggesting that the comorbidity burden may mask underlying racial disparities across cancer stages. These findings suggest that racial differences in breast cancer outcomes remain relevant and warrant further investigation, even when comorbidities are present and can obscure these disparities. Future work will explore socioeconomic factors, treatment patterns, and the cumulative impact of multiple comorbidities to clarify the drivers of these disparities and inform targeted interventions. Citation Format: M. Sanborn, M. Koury, A. Mittapalli, M. Qazi, A. Maity, S. Kjelstrom, A. Ghaneie. Impact of comorbidities and race in breast cancer survival across cancer stages abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS4-09-03.