No abstract

To investigate the tradeoff of esophageal treatment between real-time breath hold (BH) MR-guided radiotherapy (MRgRT), free breathing (FB) CT-based intensity modulated proton therapy (IMPT), and FB VMAT. We hypothesize that improved cardiopulmonary sparing would be achieved with BH MRgRT or FB IMPT compared to FB VMAT. Materials/Methods: We retrospectively evaluated differences in heart/lung dose and treatment plan conformality among 28 patients with distal esophageal cancer who were each treated with either IMPT (n Z 10), MRgRT on an MR-guided Linac (n Z 11), or VMAT (n Z 7). All were prescribed 50.4 Gy/28 fractions. IMPT and VMAT patients received a 4DCT simulation scan to quantify the internal target volume margin (ITV) for respiratory motion. MRgRT patients were simulated and treated in an inspiration BH with a 3 mm CTV to PTV margin. In lieu of a PTV margin for IMPT cases, robust optimization for range and setup uncertainty was performed on iCTV (i.e., CTV with respiratory ITV). RTOG plan quality metrics were used to evaluate target coverage (TC) (PTV V100%/PTV vol), homogeneity index (HI) (PTV D2%/ D98%), high dose conformity (PITV), low dose conformity (D2cm), and gradient (R50%). For all coverage metrics, the CTV was used. Results: Mean cardiac sparing among all patients between respective

Conclusion: OS has improved slightly in recent decades and varies by primary site. In stark contrast to our studies of patients with lung, melanoma, breast and renal cell cancers, a much higher percentage (32%) of GI patients with BM present with poor prognosis (GPA 0-1.0), highlighting the need for earlier diagnosis and better treatment. More prognostic factors have been identified. The impact of HER2/KRAS/EGFR/BRAF on OS by primary site will be presented. These data will be useful in counseling patients, refining clinical decision-making and the GI-GPA index and stratification of future clinical trials.