Abstract PS4-09-12: Adverse Social Determinants of Health Are Associated With Lower Rates of Cardiotoxicity Surveillance in Trastuzumab-Treated Breast Cancer Patients

Abstract Background: Trastuzumab poses a risk of cardiotoxicity, necessitating routine cardiac surveillance. Current guidelines recommend an echocardiogram at baseline, followed by repeat assessments every 3 months during therapy, to detect early decline in left ventricular function. Social determinants of health (SDOH) may influence patients’ ability to undergo recommended cardiac surveillance, potentially leading to delayed recognition of cardiotoxicity and worse clinical outcomes. This study investigates the impact of adverse SDOH on guideline-directed cardiac surveillance in breast cancer patients receiving trastuzumab. Methods: We conducted a retrospective cohort study using the TriNetX global federated health research network. Adult patients (≥18 years) with a diagnosis of breast cancer who received trastuzumab between January 1, 2000, and January 1, 2024, were identified. Patients were stratified into two cohorts based on the presence or absence of documented social determinants of health (SDOH) factors, identified by ICD codes Z55-65. Propensity score matching (1:1) was performed across 35 baseline characteristics to balance demographics, comorbidities and medications between cohorts. The primary outcome was the proportion of patients undergoing transthoracic echocardiogram (TTE) during 0-3 months, 3-6 months, and 6-12 months following trastuzumab initiation. Comparative analyses were conducted using risk differences with 95% confidence intervals, hazard ratios (HR) derived from Cox proportional hazards models, and Kaplan-Meier survival estimates for time-to-event analyses. Statistical significance was set at p 0.05. Results: Before matching, patients with adverse SDOH were slightly younger at index (58.5 vs. 56.7 years), more likely to be Black (18.1% vs. 12.2%), and had higher rates of comorbidities including hypertension (56.5% vs. 33.5%) and heart failure (15.4% vs. 4.2%) compared to those without SDOH risk factors. After propensity score matching, each cohort consisted of 2,554 patients with baseline characteristics well balanced between the two cohorts, and no significant differences in age, sex, race, or major cardiovascular comorbidities. Medication use, including anthracyclines and cardioprotective therapies like beta blockers and ACE inhibitors, was also similar post-matching. At 0-3 months, 33.9% of patients with documented adverse SDOH (cohort 1) received a TTE compared to 45.0% of those without SDOH risk factors (cohort 2), representing a risk difference of 11.1% (HR 0.76, 95% CI 0.69-0.83; p0.001). The median number of TTEs was 1 in both cohorts among the patients receiving at least 1. At 3-6 months; 27.7% of cohort 1 underwent TTE versus 48.9% of cohort 2, with a risk difference of 21.2% (HR 0.51, 95% CI 0.46-0.56; p0.001). Median TTE instances remained 1 in both groups. In the 6-12 month interval, surveillance remained low for cohort 1 at 31.1%, compared to 54.5% for cohort 2 with a risk difference of 23.4% (HR 0.49, 95% CI 0.45-0.54; p0.001). Among the patients receiving surveillance, the median number of TTEs was 1 in cohort 1 versus 2 in cohort 2. Conclusion: Our findings reveal significant disparities in adherence to guideline-recommended echocardiographic surveillance among breast cancer patients with adverse SDOH, persisting across all 3 intervals. There was a substantial decline in follow-up surveillance among the adverse SDOH group over time. These disparities highlight the need for targeted interventions to improve equitable cardiac monitoring and reduce long-term cardiotoxicity risk in vulnerable populations. Citation Format: D. Samat, S. Singh, V. Shah, S. Iqbal, A. Guha. Adverse Social Determinants of Health Are Associated With Lower Rates of Cardiotoxicity Surveillance in Trastuzumab-Treated Breast Cancer Patients 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 PS4-09-12.