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Laterality of Breast Radiotherapy and Ischemic Heart Disease by Cardiovascular Risk Burden

Chung SY, Noh OK

JAMA network open, 2026

23 participants

Abstract

Importance: Although modern radiotherapy (RT) techniques have reduced cardiac exposure, concerns regarding RT-induced heart disease persist. Identifying which patients are most vulnerable to cardiac toxic effects is crucial for personalized survivorship care.

Objective: To evaluate whether the association between tumor laterality and ischemic heart disease (IHD) risk varies by cumulative baseline cardiovascular risk burden.

Design, setting, and participants: This retrospective nationwide cohort study used data on 23 305 women in the Korean National Health Insurance Service database who underwent postoperative RT for breast cancer without prior IHD from January 1, 2002, to December 31, 2018. The median follow-up was 4.3 years (IQR, 2.5-6.5 years); data analysis was completed in March 2023.

Exposures: Treatment laterality (left-sided vs right-sided RT) and baseline cardiovascular risk burden (defined as a count of 6 factors: age ≥55 years, obesity, smoking, hypertension, diabetes, and dyslipidemia).

Main outcomes and measures: The cumulative incidence of IHD was estimated using competing-risk analysis. Subdistribution hazard ratios (sHRs) were calculated using Fine-Gray models.

Results: Of 23 305 patients (mean [SD] age, 51.7 [9.2] years), 11 723 (50.3%) received left-sided RT and 11 582 (49.7%) received right-sided RT. Left-sided RT was associated with a statistically significant increase in IHD risk (sHR, 1.11; 95% CI, 1.01-1.22; P = .04). No statistically significant…

How strong is the evidence?

Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 23 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

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