Cardiotoxicity Assessment in Patients Receiving Adjuvant Trastuzumab Following Anthracycline-Based Therapy

All articles of this category (opens in new window) Address for correspondence Iago Tavares Carvalho (iagotv@gmail.com) Introduction: Breast cancer is a heterogeneous disease with several molecular subtypes. Approximately 15–25% of cases are HER2-positive, which is associated with aggressive behavior and a high risk of recurrence. Anti-HER2 therapies, particularly trastuzumab—a humanized monoclonal antibody—have significantly improved outcomes. However, trastuzumab is associated with cardiotoxicity, which, although often reversible after discontinuation, may affect up to 26% of patients, mainly due to reduced cardiac function or heart failure. Objective: To determine the incidence of cardiotoxicity in patients receiving adjuvant trastuzumab after anthracycline-based chemotherapy and to explore associations with echocardiographic parameters and clinical comorbidities. Methodology: A retrospective study was conducted on 474 medical records from HER2-positive breast cancer patients treated at a single oncology center between 2013 and 2018. This study was approved by the Research Ethics Committee (CAAE: 10235919.9.0000.5293). Patients received trastuzumab for one year following anthracycline-based chemotherapy regimens. All patients underwent baseline echocardiography before initiating trastuzumab. Collected data included age, body mass index (BMI), hypertension, diabetes mellitus, and serial assessments of left ventricular ejection fraction (LVEF 1 to LVEF 4). Cardiotoxicity was defined as a significant reduction in LVEF and/or treatment interruption due to cardiac events. Patients were grouped according to the presence or absence of comorbidities. Statistical analysis included comparative tests and logistic regression models (univariate and multivariate), with a significance level set at 5%. Results: Cardiotoxicity occurred in 26.6% of patients. The median age was 53 years, and the median BMI was 27. Hypertension and diabetes were present in 35.4% and 14.0% of the cohort, respectively. Significant reductions in LVEF were observed during treatment (LVEF 2, p = 0.0002; LVEF 3 and 4, p < 0.0001). Diabetes was strongly associated with cardiotoxicity (p = 0.0029), with a 2.32-fold increased risk in the univariate model and a 2.49-fold increase in the multivariate model. Conclusion: The substantial rate of cardiotoxicity, particularly among diabetic patients, underscores the need for routine cardiac monitoring during trastuzumab therapy. Identifying high-risk individuals enables preventive strategies and enhances treatment safety in HER2-positive breast cancer. Publication History Article published online: 26 June 2026 © 2026. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution 4.0 International License, permitting copying and reproduction so long as the original work is given appropriate credit (https://creativecommons.org/licenses/by/4.0/) Thieme Revinter Publicações Ltda. Rua Rego Freitas, 175, loja 1, República, São Paulo, SP, CEP 01220-010, Brazil Bibliographical Record Iago Tavares Carvalho, Cristina Rocha de Medeiros Miranda, Kleyton Santos Medeiros, Karina Marques Vermeulen. Cardiotoxicity Assessment in Patients Receiving Adjuvant Trastuzumab Following Anthracycline-Based Therapy. Brazilian Journal of Oncology 2026; 22. DOI: 10.1055/s-0046-1825245