Modern photon based Left-Sided Breast EBRT Shows Minimal Long-Term Cardiovascular Risk: JAMA

A recent cohort study published in the Journal of the American Medical Association revealed that left-sided breast radiation was associated with only minimal increases in long-term cardiovascular risk in women treated with external beam radiation therapy (EBRT) for breast cancer over the past two decades. These findings indicate that contemporary photon-based EBRT techniques have significantly reduced the historically higher cardiac risk linked to left-sided breast cancer radiation therapy

Historically, EBRT for tumors on the left side was linked to an increased risk of long-term cardiovascular disease (CVD). However, new findings suggest that advances in radiation techniques over the past decades have significantly reduced that risk.

The study analyzed health data from 76,586 women diagnosed with unilateral breast cancer between 2002 and 2017, all of whom received EBRT. This research followed patients for a median of nearly 11 years, with some tracked for up to 15 years. The study compared long-term cardiovascular outcomes between women treated for left-sided versus right-sided breast cancer.

The primary measure was hospitalization due to cardiovascular disease. After 15 years, the cumulative incidence was nearly identical, where 13.8% was observed for left-sided cases and 13.5% for right-sided cases. This difference was not statistically significant.

Techniques such as better imaging, more precise targeting, and breath-hold methods have all contributed to lowering the average radiation dose received by cardiac tissue. Among women who already had preexisting cardiovascular disease before their cancer diagnosis, those treated for left-sided tumors showed slightly higher rates of certain conditions over time.

New diagnoses of heart failure occurred in 10.2% of left-sided cases when compared to 9.6% on the right, while ischemic heart disease was reported in 13.6% against 12.8%, respectively. Though statistically significant, these increases were described as modest.

Also, when accounting for recurrent cardiovascular events the rate was slightly higher in the left-sided group (1.72 vs. 1.63 events per 100 person-years). Still, there were no notable differences in overall mortality or cardiovascular death rates between the 2 groups, even among higher-risk patients.

The findings of this study reinforce that contemporary EBRT is much safer for the heart than it used to be. In patients with existing heart conditions, the study highlights how technological advancements in cancer care are improving long-term outcomes. 

Source:

Nakajima, E., Nguyen, L., Liu, N., Rodin, D., Amir, E., Austin, P. C., Thavendiranathan, P., & Abdel-Qadir, H. (2026). Long-term risk of cardiovascular disease after contemporary left-sided breast radiation therapy. JAMA Network Open, 9(4), e264098. https://doi.org/10.1001/jamanetworkopen.2026.4098