Therapy-induced cardiotoxicity in breast cancer patients: a well-known yet unresolved problem

Breast cancer is the second most commonly diagnosed cancer, being one of the main health issues that needs to be addressed worldwide. New therapies have led to a remarkable increase in survival rates, which is unfortunately overshadowed by their negative impact on cardiac structure and function in disease-free patients. Since anthracyclines and trastuzumab cause the most undesired outcome in breast cancer patients - cardiac-related mortality, they have been widely studied. However, other therapies (such as hormonal therapy, tyrosine kinase inhibitors, anti-VEGF drugs etc.) can also affect the cardiovascular system and lead to ischemia, hypertension or vascular thromboembolism. Even though excessive research has been conducted in thepast decades, there are still no guidelines regarding the most adequate methods neither to detect and prevent severe cardiotoxicity that can finally lead to heart failure and ultimately death nor for the further management of patients after cardiotoxicity is detected. Biomarkers of ischemia (troponins T and I) and of overload (BNP and NT-proBNP) in association with periodic echocardiographies (assessment of the global longitudinal strain) are two of the most important means used by physicians in the evaluation of cardiac disease in this group of patients. Given that no internationally accepted guidelines for screening and surveillance of different populations exist, the cardio-oncology team is crucial in the management of these patients, their collaboration resulting in individualized treatment regimens. After careful evaluation of different variables (treatment effects, malignancy status, and the patient's pre-existing conditions), a decision is made to either reduce the dosage or rate of administration, change the medication or interrupt the treatment and initiate the cardioprotective therapeutic associations. Consequently, it is an absolute necessity the development of customized treatment guidelines and the conduction of multiple clinical studies in order to demonstrate their effect on long-term survival.