Trastuzumab‐related cardiotoxicity in patients with nonlimiting cardiac comorbidity

BACKGROUND: Significant and symptomatic cardiac comorbidity is a contraindication to adjuvant trastuzumab in breast cancer patients. However, some patients with asymptomatic, nonlimiting cardiac comorbidity and normal baseline left ventricular ejection fraction (LVEF) receive adjuvant trastuzumab in the clinical practice. We sought to describe the tolerability of trastuzumab in these patients. PATIENTS AND METHODS: Retrospective analysis of patients with baseline asymptomatic, nonlimiting cardiac comorbidity receiving adjuvant trastuzumab at six Institutions between July 2007 and January 2016. RESULTS: Thirty-seven patients with HER2-positive, surgery treated breast cancer at high risk of relapse were studied. Median age was 64 years (range 36-82), median baseline LVEF 61% (range 50%-85%). Thirteen patients (35%) received trastuzumab with adjuvant anthracycline and taxane-based regimens, 19 (51%) with taxane-based, three (8%) with off-label vinorelbine and two (5%) with off-label endocrine therapy. Most frequent cardiac comorbidities were ischemic heart disease (35%), valvular disease (30%), atrial fibrillation (19%), and conduction disorders (14%). Nine patients (24.3%) experienced a cardiac event: congestive heart failure (one patient, 3%), asymptomatic LVEF reduction (six patients, 16%), and rhythm disturbances (two patients, 5%). Trastuzumab had to be discontinued either permanently (five patients, 14%) or temporarily (two patients, 5%). At the time of last follow-up visit, all patients showed LVEF within normal limits, except one who had experienced a symptomatic cardiac event (LVEF value at last follow-up 46%). CONCLUSIONS: Caution is needed in patients with significant ongoing cardiovascular risk factors, but when adjuvant trastuzumab is deemed beneficial on breast cancer outcomes, nonlimiting cardiac comorbidity should not preclude treatment.