Abstract PO2-09-06: Interaction of racial disparities on outcomes and toxicities associated with treatment of HER2+Breast Cancer- a TrinetX Database study
Authors: Vasekar Monali , Petucci Justin , Katoch Avnish , Honavar Vasant 
Published: May 2024

Objective: Investigate the interaction of racial disparities on outcomes and toxicities associated with treatment of HER2+BrCa (Breast Cancer)- a TrinetX Database study Background: HER2+BrCa is an aggressive subtype accounting for about 1/3rd of all BrCa, for which Trastuzumab based therapy remains the mainstay of treatment. While we are starting to understand the breadth of racial disparities in BrCa , the knowledge about outcomes and toxicities in relation to treatment of HER2+ BrCa is still limited. Design/Methods: In this propensity score-matched cohort study we used the TriNetX Research Network, a multi-health care organization de-identified electronic health record (EHR) database, to compare the 1-, 3-, and 5-year mortality of HER2+BrCa non-Hispanic African American (NHAA) women to a corresponding non-Hispanic White cohort (NHW). Qualification into the two race based HER2+BrCa cohorts required the presence of a C50 ICD-10-CM diagnosis code and at least one proxy for HER2 positivity such as Trastuzumab administration (index event). Cohorts were matched for age, BMI, comorbidities (HTN, DM ), and lab values using 1:1 matching with a greedy nearest neighbor search. Toxicity outcomes of interest such as cardiomyopathy, neuropathy, diarrhea, rashes, leg swelling/edema, and fatigue as well as the frequency of emergency room visits were also compared between the cohorts. The associations of observed outcome frequencies in the two cohorts were tested for significance using the chi-square test. The odds ratios and p-values, corrected for multiple hypothesis testing using the Benjamini-Hochberg procedure, are reported as an effect size and significance estimation. Results: 15983 patients met the inclusion criteria for HER2+BrCa (13611-NHW and 2372-NHAA). The mean age at the index event was 55.6 ± 12.6 years for NHAA and 57.2 ± 13.3 years for NHW. After matching the two sub-cohorts, 2303 patients remained in each. NHAA women were found to have significantly increased odds of neuropathy and cardiomyopathy for 1, 3, and 5-year time intervals after the HER2+BrCa index date, as compared to the reference NHW women (abbreviated results given in Table 1). In addition, the odds of an emergency room visit (for any reason) was found to be increased by as much as 79% in NHAA women as compared to the NHW women. The odds of experiencing fatigue/malaise, diarrhea/nausea, and rash, were reduced for NHAA women across all time intervals investigated. Odds ratios for mortality and leg swelling did not meet the significance threshold (p-value &lt; 0.05). Conclusion: This study, which examined racial disparities in outcomes and toxicities associated with HER2+BrCa, revealed significant findings. NHAA women with HER2+BrCa treated with Trastuzumab based therapy demonstrated increased odds of experiencing neuropathy and cardiomyopathy compared to their NHW counterparts. Additionally, NHAA women had a higher likelihood of emergency room visits for any reason. Conversely, NHAA women exhibited decreased odds of fatigue/malaise, diarrhea/nausea, and rash. These findings underscore the importance of considering the impact of race on HER2+BrCa outcomes and treatment toxicities and suggest the need for further research and targeted interventions to address disparities and thus enhance treatment outcomes in diverse populations.

Table 1: Representative significant Odds ratios and corrected p-values for outcomes comparing the NHAA and NHW cohorts.

Citation Format: Monali Vasekar, Justin Petucci, Avnish Katoch, Vasant Honavar. Interaction of racial disparities on outcomes and toxicities associated with treatment of HER2+Breast Cancer- a TrinetX Database study [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 PO2-09-06.