Toxicity of dose-escalated, hypofractionated helical tomotherapy for inoperable thoracic esophageal squamous cell...

Radiation therapy is an important treatment for esophageal tumors. However, there is still controversy regarding the total dose and fraction dose. The optimal dose and fractionation schedule have not yet been clearly established. Hypofractionated radiotherapy is becoming more popular, but it is unknown whether this is the optimal choice for esophageal tumors. In addition, the appropriate dose per fraction is uncertain. We performed a retrospective study to address these issues.

To report the cumulative survival and toxicity associated with the delivered dose escalation and hypofractionation schedule of radiation therapy for esophageal squamous cell carcinoma.

Forty-seven patients treated for inoperable locally advanced thoracic esophageal squamous cell carcinoma with helical tomotherapy using different total doses and doses per fraction were enrolled. Toxicity and adverse events were evaluated in all patients to determine the acute and long-term effects according to the Toxicity Criteria of The Radiation Therapy Oncology Group. Overall survival was calculated using the Kaplan-Meier method. Logistic analysis was used to identify the correlation between dose delivered to the primary tumor and the degree of toxicity. In multivariate analysis, all variables were entered in a single step using the method of backward stepwise regression.

Six patients died of bleeding related to aorto-esophageal fistulization. Four patients died of tracheo-esophageal fistulas, and 7 patients died of local recurrence. The remaining 20 patients died of metastases and multi-organ failure due to organ metastases. The dose of radiation and the dose level were positively correlated with esophageal toxicity, which was much greater with dose escalation and dose level per fraction increase.

Esophageal toxicity can be tolerated below a prescribed radiation dose of 60 Gy and less than 2.3 Gy per fraction.