NT-proBNP levels increase 16% two years after breast cancer radiotherapy, predicting cardiac dysfunction risk

Radiotherapy (RT) for breast cancer (BC), while life-saving, can induce subclinical myocardial injury, often manifesting years later as cancer therapy-related cardiac dysfunction (CTRCD). Current standard-of-care surveillance often misses these early, subtle changes. N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a well-established biomarker of myocardial stress and heart failure, but its longitudinal trajectory and predictive value specifically after BC RT, especially without concurrent chemotherapy, remain poorly characterized. Understanding these dynamics could enable earlier identification of patients at risk.

Researchers conducted a longitudinal study involving 101 BC patients who received adjuvant RT without chemotherapy. NT-proBNP levels were measured at four time points: before RT, at RT completion, and at 6 and 24 months post-RT. Comprehensive echocardiography was performed longitudinally to assess cardiac function, with CTRCD defined by 2022 ESC Cardio-Oncology guidelines. Factors influencing NT-proBNP trajectories were analyzed using linear mixed-effects models, while logistic regression assessed the association between NT-proBNP and CTRCD development.

NT-proBNP levels remained stable immediately after RT and at 6 months, but showed a significant increase at 24 months post-RT, rising by 16% (β = 0.147, p < 0.0001). Baseline NT-proBNP was a strong predictor of subsequent levels. Several factors were independently associated with higher NT-proBNP at 24 months: hypercholesterolemia (β = 0.252, p = 0.01), a specific slightly moderate hypofractionated RT regimen (20 × 2.35 Gy; β = 0.372, p = 0.0008), and aromatase inhibitor therapy (β = 0.258, p = 0.019). Notably, cardiac dose metrics from RT were not found to be significant predictors in this cohort. Over the study period, 17 patients developed CTRCD.