Background: Adjuvant trastuzumab is a highly effective targeted treatment that improves survival for patients with HER2-positive breast cancer. However, trastuzumab interruption is recommended for patients who develop treatment-induced cardiotoxicity (i.e., decline in left ventricular ejection fraction [LVEF], with or without symptoms) and can lead to an incomplete course of treatment. We studied the cardiac safety of continuous trastuzumab therapy among patients with asymptomatic declines in LVEF.
Methods: We retrospectively evaluated patients with HER2-positive breast cancer treated with adjuvant trastuzumab at our institution between 2005 and 2010. Treatment-induced cardiotoxicity was defined by an absolute decrease in LVEF of ≥10% to below 55% or an absolute decrease of ≥16%. Logistic regression was used to determine the association between candidate risk factors and treatment-induced cardiotoxicity.
Results: Among 573 patients, 92 (16%) developed treatment-induced cardiotoxicity. Trastuzumab was continued without interruption in 31 of 92 patients with treatment-induced cardiotoxicity—all were asymptomatic with LVEF of ≥50% at cardiotoxicity diagnosis with median LVEF of 53% (range, 50%-63%), and none developed heart failure during follow-up. Risk factors associated with treatment-induced cardiotoxicity included age (p = .011), anthracycline chemotherapy (p = .002), and lower pretrastuzumab LVEF (p < .001).
Conclusion: Among patients who develop asymptomatic treatment-induced cardiotoxicity with LVEF of ≥50%, continuous trastuzumab therapy appears to be safe.
Keywords: Adjuvant chemotherapy; Breast cancer; Cardiotoxicity; Heart failure; Trastuzumab.
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