Treatment Related Cardiac Toxicity in Patients Treated for Breast Cancer

Abstract

Abstract : Purpose: To determine the incidence dose/time-dependence and functional significance of regional cardiac perfusion abnormalities in patients with left-sided breast cancer treated with radiation therapy (RT) with and without doxorubicin. Methods: 160 patients underwent pre-RT single photon emission computed tomography (SPECT) cardiac perfusion imaging. Post-RT images were obtained in 125, 95, 56, 43, 24, 28, 21 and 2 patients at 6, 12, 18, 24 36, 48, 60 and 72 months post-RT. SPECT perfusion images were registered onto 3-dimensional (3D) RT dose distributions. The volume of heart in the RT field was quantified and the regional RT dose was calculated. Changes in regional and global cardiac function were assessed. Results: The incidence of new perfusion defects 6 12 16 24 36 46 and 60 months post RT was 38% 35% 38% 42% 52% 71% and 67% respectively. In the 44 patients who have longer follow-up beyond 2 years 30/44 (68%0 exhibit perfusion defects. New defects occurred in approximately 0-80% and 30-80% of patients with < 5% and 5% of their left ventricle included within the RT fields respectively. Perfusion defects were associated with changes in regional wall motion 8-26% of the time and possibly with the development of chest-pain. Patients with extensive perfusion defects may have subtle reductions in ejection fractions. Conclusions: RT causes volume-dependent perfusion defects in approximately 42% of patients within two years of RT. These perfusion defects largely persist beyond 2 years and are associated with corresponding wall motion abnormalities and possibly reductions in ejection fraction.