Racial disparities in the rate of cardiotoxicity of HER2-targeted therapies among women with early breast cancer

BACKGROUND: Human epidermal growth factor receptor 2 (HER2)-targeted therapies are highly effective at preventing breast cancer recurrence but are associated with cardiotoxicity in some patients, and minimal data are available regarding racial disparities in the incidence of this toxicity. The authors conducted a retrospective study to analyze the association of black or white race with treatment-induced cardiotoxicity and incomplete therapy among patients with HER2-positive early breast cancer. METHODS: Women with HER2-positive, stage I through III breast cancer who initiated (neo)adjuvant HER2-targeted therapy (trastuzumab with or without pertuzumab) from January 2005 to March 2015 at the authors' institution were eligible. We analyzed differences in the incidence of cardiotoxicity (a decline in the left ventricular ejection fraction to <50% AND an absolute drop in the left ventricular ejection fraction of ≥10% from baseline) and incomplete therapy (<52 weeks of HER2-targeted therapy) between black and white women in univariate and multivariable analyses. RESULTS: The authors identified 59 black patients and 157 white patients who had a median follow-up 5.2 years. The median patient age was 53 years and was similar for black and white patients. The 1-year cardiotoxicity incidence was 12% overall (95% confidence interval [CI], 7%-16%), 24% in black women (95% CI, 12%-34%), and 7% in white women (95% CI, 3%-11%). Black patients had a significantly greater probability of incomplete therapy compared with white patients (odds ratio, 4.61; 95% CI, 1.70-13.07; P =.002). High correlation was observed between a cardiotoxicity event and incomplete therapy (96% concordance). CONCLUSIONS: Black patients have a higher rate of cardiotoxicity and resultant incomplete adjuvant HER2-targeted therapy than white patients. This patient population may benefit from enhanced cardiac surveillance, cardioprotective strategies, and early referral to cardiology when appropriate. Cancer 2018;124:1904-11.