Cardiotoxicity of concomitant radiotherapy and trastuzumab for early breast cancer

Abstract

Background: Trastuzumab therapy given in combination with one of several chemotherapy regimens is currently considered the standard of care for the treatment of early-stage, human epidermal growth factor receptor-2 (HER2) -positive breast cancer. The treatment with trastuzumab is due to a significant impact on the survival part of the standard adjuvant treatment of patients with HER2-positive breast cancer. Patients treated with postoperative breast or chest wall irradiation receive trastuzumab concomitant with radiotherapy. In a small proportion of patients trastuzumab causes cardiotoxicity. Preclinical findings indicate a radiosensibilizing effect of trastuzumab in breast cancer cells, but it is not yet clear whether it radiosensibilizes cells of healthy tissues too.

Conclusions: Special attention is required when left breast or left thoracic wall is irradiated in patient receiving trastuzumab, because long-term effects of the concurrent treatment with trastuzumab and radiotherapy are not yet known. In an era where more patients are surviving a diagnosis of breast cancer, better understanding and earlier detection of therapy-induced cardiac toxicity will be of paramount importance.

Keywords: cardiotoxicity; early breast cancer; radiotherapy; trastuzumab.

FIGURE 1.

Treatment plan for postoperative irradiation of the left breast in patient with early breast cancer - Three dimensional conformal radiation therapy (3DCRT).

FIGURE 2.

Pulsed wave Doppler measurement of flow velocities through the mitral valve annulus showing normal left ventricular filling pattern. (E = early diastolic flow velocity, A = atrial contraction flow velocity).

FIGURE 3.

M mode measurement of left ventricular ejection fraction (LVEF) using the Teichholz method from the parasternal short axis view showing extremely enlarged left ventricle with severely reduced LVEF.

FIGURE 4.

Measurement of tissue Doppler velocities on the mitral annulus from the apical four chamber view showing depressed left ventricular systolic function. (x = systolic velocity, × E = early diastolic velocity, × A = atrial contraction velocity).