Breast cancer is becoming an increasingly urgent problem worldwide and in Morocco. Recent advances in the detection and treatment of cancer have improved cancer survival worldwide. However, despite major improvements in the outcome of these patients, long-term cardiotoxic side effects affect both patient survival and quality of life. Our study aimed to assess the utility of the Cardiotoxicity Risk Score (CRS) proposed by the American Society of Clinical Oncology (ASCO) to predict cardiotoxicty among Moroccan patients.

We conducted a prospective observational study from June 2018 to December 2019 in the Casablanca cardio-oncology unit, Morocco. For each patient, before iniation of treatment, we calculated The CRS that takes both patient and treatment risk factors into consideration and the patients were classified into 2 groups (high and low risk). Finally, a sensitivity analysis was performed.

Among the 413 patients included in our study, 42 patients (10,1%) experienced cardiotoxicity that was reversible with full recovery of LVEF in 31 patients (73,8%). According to the CRS, 136 of them (32,9%) were considered at high risk and 277 (67,1%) at low risk. The majority of patients who experienced cardiac events were in the high-risk group (83,4%, n=35) against 7 patients (16,6%) in the low-risk group. The sensitivity analysis showed that the CRS had a sensitivity of 83% [95% CI: 0.78, 0.92], a specificity of 65% [95% CI: 0.54, 0.71], a positive predictive value of 21% [95% CI: 0.08, 0.39] and a negative predictive value of 97% [95% CI: 0.90, 0.99]

The CRS tested in this breast cancer patients population showed good sensitivity and negative predictive value for the development of cardiotoxicity, which suggests the importance of early consultation in a cardio-oncology unit and close cardiac monitoring in high-risk patients unlike in low-risk patients who don’t really need such intensive cardiac monitoring.