Adjuvant Weekly Paclitaxel and Trastuzumab for HER2-Positive Breast Cancer without Risk Factors of Cardiotoxicity. Possibility of Omitting Cardiac Monitoring during Treatment.

Background: Although weekly paclitaxel and trastuzumab is generally considered to be less cardiotoxic than an anthracycline regimen, low baseline left ventricular ejection fraction (LVEF) of ≤55%, hypertension, and high body mass index (BMI) have been reported as risk factors for cardiotoxicity. Without these risk factors, the incidence of cardiotoxicity is expected to be minimal. Method: We retrospectively reviewed the medical records of 86 patients with HER2-positive, node-negative breast cancer between February 2012 and December 2018. Patients were selected for this study according to the following criteria: (1) patients were administered weekly treatment with paclitaxel and trastuzumab for 12 weeks, followed by trastuzumab; (2) baseline LVEF was 60% or more; (3) echocardiography was performed before, during, and at the end of treatment; (4) no hypertension or well-controlled with medication; and (5) BMI was < 30. We investigated the occurrence of cardiotoxicity. A decline in LVEF was defined as a decrease of 15% or more from baseline, or < 50% decrease in LVEF. Results: A total of 40 patients fulfilled the eligibility criteria. The median age was 55.5 (35 to 72) and median baseline LVEF was 68% (60 to 77). The median number of echocardiograms was five (3-7). Out of 40, trastuzumab were completed in 39. Among the 39 patients, no symptomatic congestive heart failure or asymptomatic LVEF decline was observed. Conclusion: In our study, no cardiotoxicity was observed in paclitaxel and trastuzumab. Assessment of cardiac function during treatment may be simplified in patients without risk factors for cardiotoxicity.