Importance: Trastuzumab improves outcomes in patients with ERBB2-positive (formerly HER2) breast cancer but is associated with treatment-induced cardiotoxicity, most commonly manifest by an asymptomatic decline in left ventricular ejection fraction (LVEF). Little is known to date regarding the long-term effects of treatment-induced cardiotoxicity on cardiopulmonary function in patients who survive trastuzumab-treated breast cancer.
Objective: To determine whether treatment-induced cardiotoxicity recovers or is associated with long-term cardiopulmonary dysfunction in survivors of ERBB2-positive breast cancer.
Design, setting, and participants: This cross-sectional case-control study enrolled patients with nonmetastatic ERBB2-positive breast cancer after completion of trastuzumab-based therapy (median, 7.0 [interquartile range (IQR), 6.2-8.7] years after therapy) who met 1 of 2 criteria: (1) cardiotoxicity (TOX group) developed during trastuzumab treatment (ie, asymptomatic decrease of LVEF≥10% from baseline to <55% [n = 22]) or (2) no evidence of cardiotoxicity during trastuzumab treatment (NOTOX group [n = 20]). Patients were treated at the Memorial Sloan Kettering Cancer Center. Fifteen healthy control participants (HC group) were also enrolled for comparison purposes. All groups were frequency matched by age strata (<55, 55-64, and ≥65 years). Data were collected from September 9, 2016, to August 10, 2018, and analyzed from November 20, 2018, to August 12, 2019.
Main outcomes and measures: Speckle-tracking echocardiography and maximal cardiopulmonary exercise testing were performed to measure indices of left ventricular function (including LVEF and global longitudinal strain [GLS]) and peak oxygen consumption (peak VO2).
Results: A total of 57 participants (median age, 60.8 [IQR, 52.7-65.7] years) were included in the analysis. Overall, 38 of 42 patients with breast cancer (90%) were treated with anthracyclines before trastuzumab. Resting mean (SD) LVEF was significantly lower in the TOX group (56.9% [5.2%]) compared with the NOTOX (62.4% [4.0%]) and HC (65.3% [2.9%]) groups; similar results were found for GLS (TOX group, -17.8% [2.2%]; NOTOX group, -19.8% [2.2%]; HC group, -21.3% [1.8%]) (P < .001). Mean peak VO2 in the TOX group (22.9 [4.4] mL/kg/min) was 15% lower compared with the NOTOX group (27.0 [5.3] mL/kg/min; P = .03) and 25% lower compared with the HC group (30.5 [3.4] mL/ kg/min; P < .001). In patients with breast cancer, GLS was significantly associated with peak VO2 (β coefficient, -0.75; 95% CI, -1.32 to -0.18).
Conclusions and relevance: Treatment-induced cardiotoxicity appears to be associated with long-term marked impairment of cardiopulmonary function and may contribute to increased risk of late-occurring cardiovascular disease in survivors of ERBB2-positive breast cancer.