Cardiovascular disease in breast cancer patients receiving chemotherapy: epidemiology and risk factors

Introduction Breast cancer is the most common malignancy among women worldwide, and chemotherapy remains a cornerstone of its treatment. However, chemotherapy can increase the risk of cardiovascular disease (CVD), which is a major cause of morbidity and mortality in cancer survivors. Understanding the prevalence and risk factors for CVD in this population is essential for improving long-term outcomes. This study aimed to evaluate the occurrence of new-onset CVD in women with breast cancer undergoing chemotherapy and to identify factors associated with increased risk. Methods We conducted a retrospective cohort study using administrative data from a Slovak health insurance company covering 1.77 million insurees (2024). We included women with breast cancer (ICD-10: C50*) who initiated chemotherapy (ATC groups L01 or L02) between 2013 and 2024. Baseline CVD status was assessed using administrative records from the two years prior to chemotherapy initiation. New-onset CVD was ascertained from the date of treatment initiation and followed for a mean of 3.8 years (SD 3.4). To identify factors associated with incident CVD, we applied multivariate Cox proportional hazards regression in the subset of patients without prior CVD. Results 10,171 women with mean age of 60.2 (SD 12.6) started chemotherapy treatment for breast cancer between years 2013 and 2024. 62.8% of them had no CVD present at the start of treatment (except for hypertension), with mean age of 55.8 (SD 11.4). Share of patients with CVD increased to 49.1% at 1 year and 63.3% at 5 years after treatment initiation. In CVD-naive patients, ischaemic heart disease was the most common CVD, with 13.0% of patients developing it within 5 years, followed by arrythmia (10.5%), atherosclerosis (8.3%), embolism and thrombosis (7.8%) and heart failure (4.7%). In patients with established CVD, the prevalence of individual diagnoses shows around two-fold increase within 5 years (Table 1). Model showed that higher age (40–64 years: HR = 1.38, ≥65 years: HR = 2.13), presence of hypertension (HR = 1.69), diabetes (HR = 1.18), chronic kidney failure (HR = 1.60) and longer chemotherapy episodes (1–4 years: HR = 1.12, ≥4 years: HR = 1.18) were significantly associated with higher CVD risk, while initial chemotherapy of L02 class was associated with lower risk (HR = 0.75). Conclusion Cardiovascular disease represents a substantial and increasing burden among women undergoing chemotherapy for breast cancer. A large proportion of initially CVD-naive patients developed cardiovascular conditions over follow-up. Among incident diagnoses, ischaemic heart disease had the highest 5-year cumulative incidence, followed by arrhythmias, thromboembolic events, and atherosclerotic disease. Together with the approximately two-fold higher prevalence observed in patients with preexisting CVD, this study highlights the need for sustained cardiovascular surveillance in breast cancer survivors.Table 1Prevalence of selected CVD