The following is a summary of “Echocardiographic functional outcomes following regional nodal irradiation for breast cancer using volumetric modulated arc therapy,” published in the July 2024 issue of Oncology by Yu et al.
Regional nodal irradiation (RNI) for breast cancer has demonstrated significant improvements in disease outcomes, but the comprehensive target coverage required often results in increased cardiac radiation exposure. Volumetric modulated arc therapy (VMAT) has the potential to reduce high-dose cardiac exposure, although it can increase the volume of low-dose exposure, raising concerns about its impact on cardiac health. This study evaluated the echocardiographic functional outcomes associated with VMAT-based RNI compared to traditional 3D conformal techniques.
Methods included the prospective enrollment of patients with breast cancer undergoing adjuvant RNI with VMAT, as approved by the Institutional Review Board. Echocardiographic assessments were conducted before radiotherapy (RT), at the end of RT, and six months post-RT. A single reader measured echocardiographic parameters, which were then analyzed for pre- and post-RT changes using the signed-rank test. Additionally, the Spearman correlation test evaluated the correlation between changes in echocardiographic parameters, and both mean and maximum heart doses.
Results from 19 evaluable patients, with a median age of 38 years, indicated that 89% (n=17) received doxorubicin and 37% (n=7) received trastuzumab/pertuzumab combination therapy. All participants were treated with VMAT-based whole-breast/chest wall and regional nodal irradiation. The average mean heart dose was 456 cGy (range: 187–697 cGy), and the average maximum heart dose was 3001 cGy (range: 1560–4793 cGy). Analysis of echocardiographic parameters revealed no significant reduction in cardiac function: the mean left ventricular ejection fraction (LVEF) was 61.8% (SD 4.4) before RT and 62.7% (SD 3.8) six months post-RT (p=0.493), while the mean global longitudinal strain (GLS) was -19.3 (SD 2.2) before RT and -19.6 (SD 1.8) post-RT (p=0.627). No individual patient showed a significant decrease in LVEF or sustained decrement in GLS. Furthermore, no correlations were found between changes in LVEF or GLS and mean or maximum heart doses (p>0.1 for all comparisons).
In conclusion, VMAT for left-sided RNI did not result in significant early decreases in echocardiographic measures of cardiac function, including LVEF and GLS, in this limited cohort. The absence of significant LVEF changes and sustained GLS decrements suggests that VMAT may be an effective strategy for minimizing cardiac exposure while delivering RNI, even in patients receiving additional high-risk treatments such as anthracyclines and HER2-directed therapies. Future studies with larger cohorts and extended follow-up are necessary to validate these findings further.
Source: sciencedirect.com/science/article/pii/S2452109424001441
