Another little piece of the heart.

Cardiac dosimetry is emerging as an important predictor of survival outcomes after radiation for locally advanced non-small cell lung cancer (NSCLC). And we are learning that the heart is more than a single critical structure—who knew? In this study, template cases were manually contoured to delineate 14 sub-structures of the heart. Nearly 1000 real-world cases were then deformably registered to each of the 5 templates for dosimetric analysis, presumably because there still aren’t enough rad onc residents to contour these manually. Increasing dose to every sub-structure was associated with survival, so they used complex models to try and rank how important dose to each substructure was relative to the others. These models pointed to the right atrium (in line with 0617), right coronary artery, and ascending aorta as the sub-structures most highly correlated with poor survival. They propose a threshold max dose-limit of 23 Gy (EQD2) to each of these sub-structures. TBL: While dose to the entire heart is important, increasing dose to the right atrium and proximal aorta might be especially associated with worse survival outcomes after radiation. | McWilliam, Int J Radiat Oncol Biol Phys 2020