Evaluation of cardiac toxicity of systemic treatments in Moroccan patients followed for localized breast cancer: Prospective observational study of 549 cases.

BACKGROUND Breast cancer is the most common cancer in women in the world and in Morocco. Anthracyclines and anti-HER2 therapy are major drugs in the therapeutic management of localized breast cancer. The most serious toxicity of these drugs is cardiotoxicity. Our work aims to assess the prevalence of this toxicity in the Moroccan population. PATIENTS AND METHODS We conducted a prospective longitudinal observational study between January 2017 and June 2018. All our patients were followed in The Cardio-Oncology Unit, 1st unit of its kind in Morocco, created thanks to the collaboration between the Mohammed VI Cancer Treatment Center and The Cardiology Departement of Ibn Rochd University Hospital in Casablanca. Eligible patients (n=549) had Stage I-III localized breast cancer, verified histologically, and a pre-treatment adequate cardiac function with a LVEF = 50%, measured with echocardiography, and received systemic cardiotoxic treatment (anthracycines, anti-her2 drugs). All patients received regular monitoring of cardiac function mainly by echocardiography. Cardiotoxicity was defined as a decrease in LVEF of 10 points and / or <50%. RESULTS A decrease in LVEF was observed in 8.4% of our patients, with 4% symptomatic heart failure. The baseline average LVEF in the cardiotoxicity group was 63.5% (50-77) versus 60.5% (60-74) in the group without cardiotoxicity. 97.1% of these patients received anthracyclines, 98% received trastuzumab against 97% and 65% in the group without cardiotoxicity respectively. Cardiotoxicity was reversible in 6.4% of patients, permanent discontinuation of cardiotoxic treatment was observed in 2.2%. A statistically significant relationship was found between cardiotoxicity and arterial hypertension (HTA) (p = 0.002), trastuzumab (p = 0.0001) and radiotherapy for left breast cancer (p = 0.023). CONCLUSION This is one of the first observational studies in Morocco with a large number of patients, which gives us an idea of the cardiotoxicity of systemic treatments in Moroccan localized breast cancer patients. Our results join those of the literature, but are still worrying and invite us, oncologists and cardiologists, to be more vigilant with this toxicity, which influences the oncological and cardiac prognosis of our patients, especially cancer survivors.