Long-Term Risk of Cardiovascular Disease After Contemporary Left-Sided Breast Radiation Therapy

Area of Science:

• Oncology
• Cardiology
• Radiotherapy

Background:

• Historically, external beam radiation therapy (EBRT) for left-sided breast cancer increased cardiovascular disease (CVD) risk.
• Modern EBRT techniques have lowered the mean heart dose, but long-term CVD outcome data are limited.

Purpose of the Study:

• To compare long-term CVD risk between left-sided and right-sided EBRT in women with breast cancer.
• To assess the impact of contemporary EBRT on cardiovascular health outcomes.

Main Methods:

• Population-based retrospective cohort study in Ontario, Canada.
• Included women diagnosed with unilateral breast cancer receiving EBRT (2002-2017).
• Follow-up through 2025, analyzing CVD hospitalizations, mortality, and specific cardiac events.

Main Results:

• No significant difference in 15-year cumulative incidence of first CVD hospitalization between left-sided (13.8%) and right-sided (13.5%) EBRT.
• Slightly higher incidence of heart failure and ischemic heart disease in women with pre-existing CVD after left-sided EBRT.
• Modestly higher rate of CVD hospitalizations (including recurrent events) for left-sided disease.

Conclusions:

• Contemporary EBRT for left-sided breast cancer is associated with minimal long-term cardiovascular risk.
• Modern photon-based EBRT techniques have substantially mitigated historical CVD risks.
• Findings support the safety of current EBRT protocols for breast cancer patients.