Abstract P2-11-09: Comparing the effects of various beta blockers on cardiovascular-related mortality in breast cancer patients

Abstract

Abstract Background: Breast cancer mortality has decreased along with advances in diagnosis and treatments. However, cardiovascular (CV) disease-related mortality is a growing concern in this population. Increased risk of CV diseases is primarily contributed by chemotherapy such as anthracyclines, anti-HER2 drugs like trastuzumab, and radiotherapy in breast cancer patients in addition to increased age. While beta blockers have been investigated to manage CV complications associated with these breast cancer treatments in general, various beta blockers have not been compared for their effects on death due to CV events. The aim of this study was to compare the effects of commonly used beta-blockers (metoprolol, carvedilol and atenolol) on CV-related mortality among older patients with breast cancer. Methods: A retrospective cohort study was conducted using the multi-year Surveillance, Epidemiology, and End Results-Medicare data (2009 to 2015). Patients diagnosed with breast cancer as the 1st or only cancer were included in this study and the date of diagnosis was the index date. The primary exposure was receipt of beta blocker monotherapy (metoprolol, carvedilol and atenolol) for at least 6 months prior to the index date. CV-related mortality was the outcome and was defined as death due to diseases of the heart. Patients were followed from the index date until the outcome or were censored at: the date of death due to breast cancer, death due to other reasons, discontinuation of the index beta-blocker, switching or addition of other beta-blockers, or end of the study period (December 31st 2015), whichever occurred first. Demographic and clinical covariates were identified using the Andersen Behavioral Model conceptual framework. Descriptive statistics were used to assess the difference in covariates between the three exposure groups. The competing risk regression model, adjusted for potential confounding variables, was used to study the association between the beta-blockers and the risk of CV-related mortality. Results: The study cohort included 6,540 patients of which 3,622 (55.4%) were metoprolol users, 989 (15.1%) carvedilol users, and 1,929 (29.5%) atenolol users. The mean age was 77.9 years for metoprolol users, 78.7 years for carvedilol users, and 76.8 years for atenolol users. A majority of the patients were White (86.8%), of Non- Hispanic or Latino ethnicity (95.1%), female (99.2%), diagnosed at stage 1 breast cancer (41.8%), of HR+/HER2- breast cancer subtype (62.8%), had between 1 to 3 Charlson comorbidities (50.6%), and did not have any other cancer after the incident diagnosis (87.8%). There were 36 (1.9%) atenolol users, 40 (4.0%) carvedilol users, and 70 (1.9%) metoprolol users with the outcome. The median time to outcome was 528 days in metoprolol users, 356 days in carvedilol users, and 411 days in atenolol users. In the adjusted model, older patients, and those with more than 3 Charlson comorbidities had a higher risk of CV-related mortality. Metoprolol was associated with a 38% (adjusted hazard ratio (aHR): 0.63, 95% CI: 0.41 to 0.96, p=0.03) reduced risk of CV-related mortality compared to carvedilol users after adjusting for the covariates. There was no significant difference in the risk of CV-related mortality between atenolol and carvedilol users. Conclusion: In older patients with breast cancer, metoprolol was associated with a reduced risk of CV-related mortality compared to carvedilol. Future prospective studies are needed to confirm these findings. Citation Format: Noor M Abdulkareem, Soumya G Chikermane, Suma Gopinathan, Michael L Johnson, Meghana V Trivedi. Comparing the effects of various beta blockers on cardiovascular-related mortality in breast cancer patients [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-11-09.