One of the more compelling data points has been the difference in cardiovascular outcomes between women treated for left- versus right-sided disease. For obvious anatomical reasons, therapy for left-sided tumors results in a significantly higher radiation dose to the heart. In the current study, patients with left-sided breast cancer had significantly higher rates of cardiac complications, particularly after >10 years from the time of radiation therapy. Even more convincing was the fact that the components of “cardiovascular deaths,” which are most plausibly influenced by radiation (heart failure, valvular disease, ischemic disease) were the most dramatically affected, whereas no such findings were seen in other cardiac diseases (e.g., hypertensive disease, “pulmonary heart diseases”), which are less plausibly affected by radiation. Several other studies of >10 to 15 years follow-up have found clear evidence of excess cardiovascular risk in patients treated for left-sided disease (5- 7). Increased use of anthracyclines and anti-HER2 therapy over the last 10 to 20 years adds another wrinkle to the equation, as their use likely further increases the cardiac risk (8).