Cardiotoxicity manifestations in metastatic breast cancer patients treated with trastuzumab as first line.

Abstract

e13011 Background: Trastuzumab is a monoclonal antibody that targets the human epidermal growth factor receptor-2 (HER2). Its use may result in cardiotoxicity. There are no formal guidelines for left ventricular ejection fraction (LVEF) monitoring in patients with metastatic disease treated with trastuzumab. Our local guideline include an echocardiogram every 3 months for these patients. Methods: We collected data from electronic records and hard copy files of patients treated with Trastuzumab as first line, between the years 2011-2014. Results: One hundred patients met the inclusion criteria. Median treatment duration of all patients was 30 months, with an average of 12 echocardiogram follow-ups per patient. Ninety-nine patients (99%) received additional chemotherapy. Thirty patients (30%) also received Pertuzumab. Ten (10%) of the eligible 100 patients showed significant decline in EF (≥10%) to a final LVEF of < 50%. The median follow-up duration of these patients was 52 months. Median EF at the beginning of treatment was 61.5% in all patients. Cardiotoxicity occurred at an average of 23 months [median 18 months] after beginning of Trastuzumab treatment (range; 3-54 months), with an average EF decline of 14% (range; 10-18%). Three patients (30%) required treatment change due to the decline in EF. Temporary cessation of treatment was necessary in 4 (40%) of the patients for a period of time between 4 weeks to 8 months. The remaining 3 patients (30%), although developing significant decline in EF, did not require treatment cessation or change. None of the 10 patients presented any other clinical sign of cardiotoxicity. In the group with cardiac events, there were no previous reports of congestive heart failure (CHF), ischemic heart failure (IHF), myocardial infraction (MI) or diabetes. Only one patient was a smoker and another received hormone replacement therapy. The average age of this group at the time of diagnosis of metastatic disease was younger (50.6 vs. 55.8, P-value 0.5). Conclusions: Monitoring heart function by trimonthly echocardiogram does not seem to be the optimal monitoring modality in metastatic breast cancer patients who receive a trastuzumab-containing regimen as first line. This study results suggest that less frequent monitoring may be sufficient, thus diminishing patients' inconvenience and allowing better allocation of health care resources.