Evaluation of early cardiotoxicity in HER2-positive breast cancer patients receiving radiotherapy and concurrent trastuzumab.

Background: Overexpression of human epidermal growth factor receptor 2 (HER-2) is associated with aggressive disease in breast cancer. Trastuzumab and radiotherapy are standard treatments for patients with HER-2 + breast cancer, but they may increase the risk of cardiotoxicity.

Aim: This study aimed to assess early cardiotoxicity in patients receiving radiotherapy (RT) and concurrent trastuzumab.

Method: The study included 116 patients with HER-2 + breast cancer who received concurrent treatment with trastuzumab and RT (52 right-side; 64 left-side). Five left ventricular ejection fraction (LVEF) measurements were performed: one before treatment and four subsequent measurements taken at three-month intervals. LVEF was also assessed before (preRT-EF) and after (postRT-EF) radiotherapy.

Results: The baseline LVEF was 62.27 ± 5.5%, while the 12-month LVEF was 59.8 ± 5.8% (p < 0.05). In subgroups, post-RT LVEF values ​​were significantly lower than pre-RT LVEF values (p < 0.05). No significant difference was found between the reduction in LVEF for patients receiving 50 Gy and 60 Gy doses. Moreover, the contribution of regional lymph node irradiation to the decrease in LVEF could not be demonstrated. A positive correlation was found between the total trastuzumab dose and the decrease in LVEF from preRT to postRT. Additionally, a positive correlation was observed between the total taxane dose and the reduction in LVEF from baseline to 9 months, both in the overall group and in the left breast cancer group.

Conclusion: In our study,it was found that not only trastuzumab but also taxane-based agents could be cardiotoxic. However, no connection was found between RT doses and the decrease in LVEF.