Heart health.

Top Line: Intensity modulated radiation (IMRT) techniques for breast cancer seems like it could reduce heart toxicity.
The Study: Decisions for breast and comprehensive nodal irradiation have gotten complicated, particularly when it comes to the internal mammary nodes. We know there is a cancer benefit to treating them. At the same time, we know there is harm in delivering too much radiation to the heart. Can more complex radiation planning techniques strike a happy medium? In this trial,women with node positive left-sided breast cancer were randomized to conventional 3D-conformal radiation with free breathing or IMRT with a deep inspiratory breath hold. Before we get too carried away, let’s remember that it took thousands—thousands—of patients to demonstrate both the cancer benefit and potential cardiac toxicity of left sided comprehensive nodal irradiation. Nevertheless, the primary outcome of this ambitious (n=54) trial was cardiac perfusion changes at one year. Importantly, each patient had acceptable plans generated with both modalities prior to randomization to minimize bias. Each arm was conventionally-fractionated(ish), with the 3D arm using a sequential boost and the IMRT arm a simultaneous boost. IMRT uniquely utilized restricted beam angles to avoid contralateral dose spill and to specifically avoid cardiac structures. In other words, IMRT significantly reduced the volume of lung and heart receiving moderate doses as well as the mean doses to those structures. Too bad there were no differences in cardiac perfusion at one year. The authors really harp on preserved left ventricular ejection fraction (LVEF, a secondary endpoint) with IMRT, though that conclusion is a little iffy unless you believe IMRT actually works to bolster LVEF.
Bottom Line: IMRT for comprehensive nodal irradiation of the left breast and chest wall can reduce moderate dose exposure to the lungs and heart, but it doesn’t clearly reduce changes in cardiac perfusion. | Jagsi, Int J Radiat Oncol Biol Phys 2018


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