No changes in myocardial perfusion following radiation therapy of left-sided breast cancer: A positron emission tomography study

Abstract

Adjuvant radiation therapy (RT) for breast cancer has improved overall survival. However, incidental exposure of the heart has been linked to development of radiation-induced heart disease. The aim of this study was, in a cohort of asymptomatic post-irradiation breast cancer patients, to investigate changes in myocardial blood flow (MBF) and presence of perfusion defects in myocardial perfusion positron-emission-tomography (PET) in the irradiated myocardium. Twenty patients treated with RT for left-sided breast cancer underwent 13N-ammonia myocardial perfusion PET 7(±\u20092) years after breath adapted RT to a total dose of 48 Gy given in 24 fractions. No differences in rest or stress MBF were noted between the irradiated and non-irradiated myocardium (1.29 (±\u20090.29) vs 1.33 (±\u20090.29) mL/g/min, ns; 2.74 (±\u20090.59) vs 2.78 (±\u20090.66) mL/g/min, ns, respectively). One patient demonstrated a myocardial perfusion defect localized in the irradiated anterior wall myocardium. Although limited by a small sample size, early signs of cardiac injury detected by NH3 myocardial perfusion PET was at least not frequent in our cohort of patients treated with a modern RT technique for left-sided breast cancer, even 7 years after treatment. The findings however, may not rule out subsequent development of myocardial injury.