Radiobiological evaluation of simultaneously dose-escalated versus non-escalated intensity-modulated radiation therapy for patients with upper thoracic esophageal cancer

Abstract

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

Acknowledgments

This work was sponsored by National Natural Science Foundation of China (81602667), Science and Technology Planning Project of Guangdong Province (2016ZC0166), Medical Scientific Research Foundation of Guangdong Province (A2015534), Shantou University Medical College Clinical Research Enhancement Initiative (201424), Collaborative and Creative Center, Molecular Diagnosis and Personal-ized Medicine, Shantou University, Guangdong Province, People’s Republic of China.

Author contributions

Each author had participated sufficiently in the work to take public responsibility for appropriate portions of the content. BTH and CZC conceived and designed the experiments. LLW, LJG, LYX, and JZC performed the experiments. BTH, LLW, LJG, LYX, and RHH collected the data. PXL analyzed the data. BTH wrote the paper. DRL and CZC revised the paper. All authors contributed toward data analysis, drafting and revising the paper and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.