Adjuvant Breast Cancer Treatments Induce Changes in Homoarginine Level - A Prospective Observational Study.

Aim: To identify patients with breast cancer at risk for cardiotoxicity, we evaluated homoarginine (HA) behavior during adjuvant treatment. Patients and Methods: Eighty-one patients received radiotherapy (RT) with or without endocrine treatment, and 19 received chemotherapy, RT and endocrine therapy. Serum HA, asymmetric dimethylarginine (ADMA) and high-sensitivity cardiac troponin T (hscTnT) were measured and echocardiography was performed before chemotherapy, and before and after RT. Results: In chemo-naive tamoxifen users HA increased during RT from a median (IQR) of 2.47 (1.61-3.35) to 2.86 (1.93-4.23) mu M (p=0.028) and remained stable in patients with aromatase inhibitor and in those without endocrine therapy. Tamoxifen users were mostly spared from echocardiographic changes. In chemotherapy-treated patients, HA decreased during chemotherapy (p=0.001) from 1.46 (1.01-2.18) to 0.91 (0.71-1.29) mu M, and increased (p=0.004) to 1.19 (0.83-1.63) mu M during RT, remaining lower than at baseline (p=0.014). Echocardiographic changes were observed during chemotherapy. Conclusion: HA decrease during chemotherapy could indicate an increased risk of cardiovascular morbidity. Additionally, HA increase in tamoxifen users may reflect a cardioprotective effect of tamoxifen.