Racial Disparities in the Rate of Cardiotoxicity of HER2-Targeted Therapies Among Women With Early Breast Cancer

Authors: Litvak, A. et. al.
Source: Cancer doi: 10.1002/cncr.31260
onlinelibrary.wiley.com/doi/abs/10.1002/cncr.31260

Women with HER2-positive breast cancer have significantly improved survival when they are treated the HER2-targeted therapy. Trastuzumab and pertuzumab may be used in preoperative (neoadjuvant) or postoperative (adjuvant) settings. These therapies do have side effects of cardiotoxicity. The cardiac muscle may dysfunction, leading to reduce left ventricular ejection fraction. Most cases of dysfunction are asymptomatic and resolve when therapy is discontinued. Other factors for the dysfunction include anthracycline chemotherapy, (another treatment associated with cardiac dysfunction), older patient age, history of cardiac dysfunction, hypertension and obesity. The investigators note that some studies have evaluated differences in cardiac function between black and white women, which suggested that the former group had increased risk of dysfunction. However, the number of black women participating in the studies were small.

This project evaluated women with stages I-III HER2-postive breast cancer who received targeted therapy between 2005 and 2015. Cardiac events and overall outcomes were assessed.

Just over 200 women were included; 59 were black and 157 were white. The black women had higher rates of cardiovascular risk factors such as a smoking history, diabetes, hypertension and hyperlipidemia.

The risk of cardiotoxicity was much higher for black women than for white women, and this difference was statistically significant. When controlling for age, cancer stage, cardiovascular risk factors and anthracycline therapy, race was a significant predictor of cardiotoxicity. A much larger number of black women stopped HER2-targeted therapy because of cardiotoxicity. Investigators did find that the black women had worse overall survival compared to the white women, but noted that this may have been due to multiple factors and not cessation of HER2-targeted therapy.

While this study found that race predicted cardiotoxicity when other factors were equal, the investigators still note that the differences in this study could have been due to a greater prevalence of cardiovascular risk factors among the black participants. They also mention that genetics may play a role for some individuals.

While this study was retrospective and had a small sample size, the findings are consistent with prior studies. Further investigation is needed into the effects of HER2-targeted therapy among black women with breast cancer. The researchers recommend taking specific efforts to include women of color in future breast cancer treatment trials.