Background: Approximately 25% of female breast cancers in Asia were also found to overexpress HER2. Trastuzumab is a humanized monoclonal antibody that consists of two antigen-specific sites that bind to the juxtamembrane portion of the extracellular domain of the HER2. Label information of trastuzumab also addresses the advices regarding cardiac monitoring prior and during trastuzumab treatment course. According to a Cochrane database search, 8 large randomized controlled studies with a total of 11,991 breast cancer patients, trastuzumab significantly increased the risk of left ventricular ejection fraction decline ( RR 1.83; 90% CI 1.36 to 2.47, P = 0.0008).
Objectives: The purpose of this study is to investigate long term cardiotoxicity in patients with human epidermal growth factor receptor 2 (HER2) positive breast cancer treated with trastuzumab.
Methods: We gathered operable, HER2- positive breast cancer patients from January 2014 to June 2019. A total of 155 cases received 6 mg/kg of trastuzumab every 3 weeks after a loading dose of 8 mg/kg. The left ventricular ejection fraction (LVEF) was measured for regular monitoring and assessment of cardiotoxicity.
Results: The median treatment was 13 cycles in Her-2 positive breast cancer patients who received trastuzumab. 78 cases (50.3%) tested for LVEF before using trastuzumab and baseline mean LVEF value of 66.41% ± 0.07%. 77 cases (49.7%) no tested for LVEF before using trastuzumab. 25 cases (16.1%) followed up LVEF after using trastuzumab and baseline mean LVEF value of 60.01% ± 0.13%. 130 cases (83.9%) no followed up LVEF after using trastuzumab. LVEF level dropped in 12 cases (15.4%) after trastuzumab treatment. 2 patients (2.6%) experienced grade III cardiotoxicity.
Conclusions: Trastuzumab administration was generally safe, with reversible cardiac toxicity. However, the potential cardiotoxicity of trastuzumab should be carefully monitored during therapy.
