Introduction: Expression of steroid receptors and HER2 overexpression in breast cancer cells are predictive and prognostic factors. Overexpression of HER2 allows the use of immunotherapy, in which the most serious side effect is cardiotoxicity. The aim of this study was to evaluate the influence of steroid receptor status on cardiotoxicity risk in HER2 breast cancer patients receiving trastuzumab both in adjuvant treatment and in the case of disease dissemination. This study also assessed well-known cardiac risk factors.
Material and methods: The study was conducted on 166 patients who received immunotherapy in the Clinical and Experimental Oncology Department, between the years 2006 and 2012.
Results: A predisposition to cardiac side effects (13% vs. 5%) in patients with negative steroid receptor status was observed (p = 0.08). The decrease of left ventricular ejection fraction (LVEF) (12% vs. 0) and cardiac adverse side effects (2% vs. 0) were detected only in ER-/PR- patients but without statistical significance. Discontinuation of therapy because of cardiotoxicity was associated with negative receptor status (33% vs. 7%) (p = 0.019). Irrespective of steroid receptor status, older age of patients (p = 0.009) and previous radiotherapy to the left side of the chest (p = 0.02) were associated with the occurrence of cardiotoxicity and decrease of LVEF. In patients who received previous anthracycline-based chemotherapy, acute cardiac side effects were observed significantly more often (p = 0.01).
Conclusions: There was no influence of steroid receptor status on the cardiac side effects. Breast cancer type containing Erb-B2 overexpression was associated with predisposition to cardiotoxicity. The results require confirmation in a larger group of patients.