(P17) Standard Versus Dose-Escalated Radiation Therapy for Management of Esophageal Cancer: A Retrospective Review

Abstract

High dose radiation therapy for esophageal cancer has not been shown to improve survival or locoregional control in prior studies. This study was aimed at comparing overall survival (OS), progression-free survival (PFS), and toxicity in patients treated with standard versus dose-escalated radiation therapy for esophageal cancer. Patients treated for Stage IA-IIIC adenocarcinoma or squamous cell carcinoma of the upper, mid, and lower esophagus or gastroesophageal junction between January 2008 and July 2014 were retrospectively reviewed. Patients included those treated with definitive and neoadjuvant chemoradiation. Patients with metastatic disease at presentation, and prior radiation to the esophagus were excluded. Dose-escalation was considered a total dose over 50.4Gy. Toxicity was graded per CTCAE version 4.03. Kaplan-Meier survival analysis was completed. Descriptive statistics and Fisher’s Exact tests were used where applicable. A total of 73 patients were included in the analysis. 55 patients received standard dose radiation (median 50Gy, range 45-50.4Gy), while 18 patients received dose-escalation (median 59.7Gy, range 51-68Gy). Median time to follow-up was 22.75 months. There was no significant difference in the curves for PFS (p=.70) or OS (p=.59). Median PFS was 30.3 (95% CI 15.2-51.2mo) in the standard dose group, and 47.0 (95% CI 16.3-47.0mo) in the dose-escalated group. Median OS was 68.6mo (95% CI 21.2-69.8mo) in the standard dose group, and 48.6mo (95% CI 18.6-57.5mo) in the dose-escalated group. When comparing only patients who received definitive chemoradiation (n=22 standard, 14 dose-escalated), there was a trend towards significance for PFS (p=.051), but OS was not significantly different (p=.60). Median PFS in this case was 7.2mo (95% CI 5.2-15.2mo) in the standard group and 33.7mo (95% CI 9.9-33.7mo) in the dose-escalated group, while median OS was 14.6mo (95% CI 10.1-68.6mo) in the standard group and 32.4mo (95% CI 16.8-51.2mo) in the dose-escalated group. The rate of any gastrointestinal toxicity did not differ significantly between the two groups (96.3% standard dose vs 94.4% dose-escalated, p=1.0). The rates of any esophagitis (56.3% standard dose vs 77.8% dose-escalated, p=.16) and grade 3 esophagitis (3.6% standard dose vs 16.7% dose-escalated, p=.09) did not differ significantly between the groups. The pathologic complete response rate was 30.3% in the standard dose group, and 25% in the small group of dose-escalated patients who underwent surgery (p=1.0). In this retrospective study, results indicated no significant difference in overall or progression-free survival when comparing standard and dose-escalated radiation for esophageal cancer. There was a trend towards significance for PFS when looking only at those patients who received definitive chemoradiation. There was no significant difference in the rates of esophagitis, or gastrointestinal toxicity overall. The rate of pathologic complete response did not differ. Further research is warranted, especially in patients undergoing definitive chemoradiation, but standard dosing should remain the standard of care in the interim.