Exploring the relationship between oral health and cancer therapy related cardiac dysfunction in HER2-positive breast cancer patients

Background Anthracyclines and HER2-targeted therapies such as trastuzumab are central to the management of breast cancer but are limited by their potential to cause chemotherapy-related cardiac dysfunction (CTRCD). Anthracycline cardiotoxicity is primarily driven by oxidative stress and mitochondrial injury, while trastuzumab impairs HER2-mediated cardiomyocyte repair, especially in patients with prior anthracycline exposure. Identifying modifiable factors that may mitigate CTRCD has become increasingly important to maintain treatment continuity and improve outcomes. Emerging evidence suggests that systemic inflammation and oxidative stress, both influenced by oral health status, may contribute to CTRCD vulnerability. This study therefore investigated the association between oral health and the incidence and severity of CTRCD in breast cancer patients receiving trastuzumab with or without prior anthracycline therapy. Methods A retrospective cohort study was conducted at our Cancer Care and Research Centre among breast cancer patients treated with trastuzumab and followed for one year between 2022 and 2025. (Figure 1) Oral health was assessed via the DMFT index, and periodontal staging/grading was performed on the basis of baseline dental evaluations performed before the initiation of chemotherapy containing trastuzumab. Patients were then categorized into good or poor oral health groups. CTRCD was diagnosed and classified via echocardiographic findings, with recovery time documented. The primary outcome was CTRCD incidence; secondary outcomes included recovery time, cardiac biomarkers, symptoms and drop in left ventricular ejection fraction (LVEF). Results Among patients with CTRCD, 64.5% had poor oral health, whereas 33.8% had poor oral health in the control group (p < 0.001). Poor oral health was significantly associated with increased CTRCD risk (OR = 3.54; 95% CI: 1.76–7.14), delayed recovery (8 weeks vs. 4 weeks, p = 0.011), and a 6-fold increased likelihood of significant EF decline (>10%) (p = 0.0023). Associations with cardiac biomarkers (BNP and troponin) tended toward significance. (Figure 2) Conclusions Poor oral health is significantly associated with an increased risk and delayed recovery of CTRCD in patients receiving HER2-targeted therapy. These findings highlight oral health as a modifiable risk factor that may impact cardiac and oncologic outcomes. Future randomized controlled trials are needed to further investigate the potential benefits of dental interventions in preventing CTRCD.