To evaluate the cardiac risk associated with left-sided versus right-sided breast radiotherapy in a large cohort of women, emphasizing the comparative aspect.
Key Findings:
15-year cumulative incidence of first cardiovascular hospitalization was similar for left-sided (13.8%) and right-sided (13.5%) EBRT (P = .43).
Adjusted hazard ratio for cardiovascular hospitalization was 1.02 (95% CI, 0.98-1.06).
Small increases in new heart failure (10.2% vs 9.6%) and ischemic heart disease (13.6% vs 12.8%) were noted for left-sided EBRT, though these differences were not statistically significant.
Higher CVD hospitalization rates were observed for left-sided disease when counting recurrent events (1.72 vs 1.63 per 100 person-years; hazard ratio, 1.05; 95% CI, 1.00-1.11).
Interpretation:
Contemporary photon EBRT has largely mitigated major cardiovascular risks historically associated with left-sided treatment, although small excess risks remain, particularly in younger women and those receiving chemotherapy, highlighting the need for tailored clinical approaches.
Limitations:
Laterality is an imperfect proxy for cardiac dose exposure, and administrative data cannot identify patients with higher-than-typical cardiac exposure.
The study may understate risk in patients receiving regional nodal radiotherapy due to lack of individual dosimetry.
Conclusion:
Counseling should focus on patient-specific absolute-risk framing rather than laterality alone, emphasizing heart-sparing techniques and cardiovascular risk prevention for high-risk patients.
