OncoTargets and Therapy (Apr 2017)
Radiobiological evaluation of simultaneously dose-escalated versus non-escalated intensity-modulated radiation therapy for patients with upper thoracic esophageal cancer
Abstract
Bao-Tian Huang,1,* Li-Li Wu,1,* Long-Jia Guo,1,* Liang-Yu Xu,1,* Rui-Hong Huang,1 Pei-Xian Lin,2 Jian-Zhou Chen,1,3 De-Rui Li,1 Chuang-Zhen Chen1 1Department of Radiation Oncology, Cancer Hospital of Shantou University Medical College, Shantou, 2Department of Nosocomial Infection Management, The Second Affiliated Hospital of Shantou University Medical College, Shantou, People’s Republic of China; 3CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom *These authors contributed equally to this work Objective: To compare the radiobiological response between simultaneously dose-escalated and non-escalated intensity-modulated radiation therapy (DE-IMRT and NE-IMRT) for patients with upper thoracic esophageal cancer (UTEC) using radiobiological evaluation. Methods: Computed tomography simulation data sets for 25 patients pathologically diagnosed with primary UTEC were used in this study. DE-IMRT plan with an escalated dose of 64.8 Gy/28 fractions to the gross tumor volume (GTV) and involved lymph nodes from 25 patients pathologically diagnosed with primary UTEC, was compared to an NE-IMRT plan of 50.4 Gy/28 fractions. Dose-volume metrics, tumor control probability (TCP), and normal tissue complication probability for the lung and spinal cord were compared. In addition, the risk of acute esophageal toxicity (AET) and late esophageal toxicity (LET) were also analyzed. Results: Compared with NE-IMRT plan, we found the DE-IMRT plan resulted in a 14.6 Gy dose escalation to the GTV. The tumor control was predicted to increase by 31.8%, 39.1%, and 40.9% for three independent TCP models. The predicted incidence of radiation pneumonitis was similar (3.9% versus 3.6%), and the estimated risk of radiation-induced spinal cord injury was extremely low (<0.13%) in both groups. Regarding the esophageal toxicities, the estimated grade ≥2 and grade ≥3 AET predicted by the Kwint model were increased by 2.5% and 3.8%. Grade ≥2 AET predicted using the Wijsman model was increased by 14.9%. The predicted incidence of LET was low (<0.51%) in both groups. Conclusion: Radiobiological evaluation reveals that the DE-IMRT dosing strategy is feasible for patients with UTEC, with significant gains in tumor control and minor or clinically acceptable increases in radiation-induced toxicities. Keywords: radiobiological evaluation, dose-escalated, non-escalated, intensity-modulated radiation therapy, esophageal cancer
