Patients with left-sided breast cancer who receive adjuvant breast or chest wall radiation have increased risk of treatment related cardiovascular morbidity. The risk of cardiac morbidity and mortality is increased when a patient receives radiation following adjuvant chemotherapy and Herceptin. The dose-volume histogram (DVH) parameters associated with increased cardiac toxicity include volume of heart irradiated, total radiation dose received by the left ventricle (LV), V25 and mean cardiac dose. Even though modern RT treatments like 3DCRT and IMRT can reduce the mean dose to the heart, the maximum dose to the left side of the heart/LV may not be reduced if the target is close to the heart. The hypothesis is that DIBH RT can safely and effectively reduce the heart dose, especially the dose to the LV, that could lead to reduction in the incidence of radiation induced cardiovascular morbidity and mortality.
Radiotherapy has detrimental effects on cardiac function due to remodeling of the cardiac tissue that receive radiation. We believe that the radiation related acute effects on heart tissue can be detected with cardiac functional MRI. The study will quantify the acute RT related effects. To our knowledge, cardiac MRI has not been explored as a non invasive technique to quantify RT +/- chemotherapy related effects.
