Mapping clinical and imaging factors that might predict cardiac events in breast cancer patients

Breast cancer is the most common in women, with a 90% overall survival at 5 years. Cardiotoxicity is a side effect that can modify their morbidity and mortality. Its low prevalence and long latency period have challenged the establishment of a strategy for early detection and prevention.

To investigate the association between coronary artery calcium (CAC) in planning computed tomography (CT) and cardiac events.

Retrospective cohort of 873 breast cancer patients (460 right-side; 413 left-side) treated with radiotherapy (2013-2022). We extract the Hounsfield Unit to quantify the CAC degree from the heart structure in the planning CT. We used IBM-SPSS software (V 29.0 Armonk, NY) for the statistical analysis.

After a median follow-up of 4.52 years (range: 2.42-6.22 years), the cardiac events incidence was 1.95% vs 5.1% in right and left breast cancer, respectively. The mean heart dose was higher in cases with cardiac events (6.74Gy vs 2.28Gy; p<0.01). CAC score>0 was detected in 32.76% of planning CT and was more frequent in the elderly and those with cardiovascular risk factors (p<0.01). Patients with cardiac events presented a CAC score>0 in 41.4% of cases. However, the overall survival in these patients did not differ from those without CAC (p=0.58).

Patients with cardiovascular risk factors and a mean cardiac dose greater than 5 Gy are at increased risk of cardiotoxicity and should be referred for Cardio-Oncology evaluation. The application of the CAC score in CT planning could be a valuable screening test that requires further study.