Kinetics of B-type natriuretic peptide plasma levels in patients with left-sided breast cancer treated with radiation therapy: Results after one-year follow-up

Purpose: To analyze temporal changes of B-type natriuretic peptide (BNP) used as index of heart remodeling in left-sided breast cancer patients after radiotherapy (RT) and its relationship with dosimetric parameters.Methods and materials: BNP and dose-volume parameters for heart and ventricle were collected in 59 patients (median age 58.0 years) during a 1-year follow-up. Biochemical measurements were performed before the RT treatment (T0), at 15 days during RT (T-15day), at the end of RT (T-endRT), and then at 1, 3, 6, 9, 12 months (T1, T3, T6, T9 and T12). A logistical regression analysis was performed to identify demographic characteristics, dosimetric variables and risk factors associated with increased values of BNP.Results: The ratio between the BNP value at T12 and the BNP value at T0 (BNPT12/BNPT0) increased significantly (p < 0.01). A significant association was found between the variation of BNP values after 1 year and the isodose received by 50% of the volume (D50% [Gy]) both to the heart (p = 0.03) and ventricle (p = 0.04).Conclusions: BNP plasma levels could provide additional information about subclinical RT-induced cardiotoxicity earlier than traditional ecocardiographic data.