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Recent data show that overall survival after endoscopic mucosal resection (EMR) is similar to esophagectomy, however, limited data exists regarding the comparative efficacy of definitive radiotherapy (RT) for the treatment of T1N0 esophageal cancer. We sought to investigate the patterns of practice for the treatment of T1N0 esophageal cancer in the United States as well as to evaluate the comparative efficacy of esophagectomy vs EMR vs RT. Materials/Methods: Patients with clinical T1N0 esophageal carcinoma who underwent esophagectomy, EMR or RT (45 e 70 Gy) were identified from the National Cancer Database (NCDB) from 2004 to 2013. Univariate (UVA) and multivariable (MVA) effects of treatment type on survival were assessed using Cox proportional hazards regression. Overall survival (OS) was compared using Kaplan-Meier analysis and the log-rank test. Variables with p<0.001 were included in the MVA for OS. Results: 6,262 met criteria for inclusion in this study: 2,995 (48%) underwent esophagectomy, 2,130 (34%) underwent EMR and 1,137 (18%) underwent RT. Only 3 patients underwent esophageal brachytherapy. Median age was 68 years, and patients undergoing RT were older (72 y) compared to those undergoing esophagectomy (65 y) or EMR (70 y) (p<0.0001). In the esophagectomy, EMR and RT groups, 70%, 75% and 72% of patients had a Charlson score of 0, respectively. Median follow-up was 34 months. Median RT dose was 50.4 Gy and 78% underwent concurrent chemotherapy. 30 day mortality was 3.1% for esophagectomy and 0.6% for EMR. In recent years, EMR was more frequently utilized, rising from 23% to 43% whereas esophagectomy and RT were less frequently utilized in the same time period (p<0.0001). RT was more frequently utilized at non-academic centers than academic centers, 30.3% vs 9.3%, p<0.0001. Of the patients who underwent esophagectomy, 614 (21%) were upstaged. On MVA, patients with Charlson/Deyo score 1 (HR 1.2, pZ0.0003), older age (HR 1.03, p<0.001), Medicaid or no insurance (HR 1.5, pZ0.003), treatment at non-academic centers (HR 1.1, pZ0.009) and squamous histology (HR 1.3, p<0.001) were predictors of worse OS. There was no difference in OS between patients undergoing esophagectomy or EMR (pZ0.4) and this finding persisted when analysis was limited to T1a patients (pZ0.69). Patients requiring post-operative chemotherapy had a worse OS (HR 1.3, p<0.001). Patients who received definitive RT had a worse OS compared to patients who underwent esophagectomy or EMR (HR 1.8, p<0.001). Conclusion: EMR is increasingly utilized compared to esophagectomy and definitive RT for early esophageal cancer, whereas the utilization of esophageal brachytherapy was rare. Adoption of EMR in lieu of esophagectomy has not compromised survival. Patients undergoing esophagectomy and EMR had a superior OS compared to those who underwent definitive RT. Patients undergoing definitive RT appear to have unfavorable features likely affecting OS.

Purpose: To investigate the beam attenuation and beam spoiling properties of the Calypso electromagnetic array used for patient localization and tumor tracking during the radiation delivery Method and Materials: One of the main components of the Calypso 4D system is an electromagnetic array placed above patients who are implanted with transponders. We measured both the narrow and board beam attenuation properties of the array including the effect of beam angle (0 to 90 degree). A photon diode placed in cylindrical graphite buildup cap was used for narrow geometry, field size of 1 cm ×1 cm, and a 0.6 cc cylindrical farmer chamber placed in a polystyrene buildup cap for broad geometry, field size of 10 cm × 10 cm. For broad beam geometry, distances of 2, 5, and 10 cm between the chamber and the array were used. Measurements were performed using a Varian Clinac IX linear accelerator with 6 MV and 15 MV photon beams. Beam spoiling properties of the array was studied by placing the array above a water equivalent phantom with an imbedded Markus parallel plate chamber and measuring depth doses. Depth doses were measured for both 6 MV and 15 MV photon beams with 10 cm × 10 cm field size for distances of 2, 5, and 10 cm between array and phantom surface. Results: Narrow beam geometry attenuation is 1.5 % and 1.3% for 6 MV and 15 MV beam respectively. Beam angle dependence is more pronounced at angles greater than 70 degrees with attenuation greater than 5%. Broad beam attenuation, in clinical cases, is nonexistent due to scatter contribution. Spoiling properties could be appreciable. Conclusion: Attenuation properties of the array may be ignored for treatment delivery for most clinical cases. Spoiling effect could be appreciable depending on array distance to patient surface.

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