Jimm Grimm, PhD, Sheena Jain, MD, Vitali Moiseenko, PhD, Mark McLaughlin, MD, Scott Herbert, MD, Joost J. Nuyttens, MD, PhD; Holy Redeemer Hospital; University of California, San Diego; WellStar Kennestone Hospital; Abington Memorial Hospital; Erasmus Medical Center
PURPOSE AND OBJECTIVES: Mediastinal critical structures, such as the trachea, bronchus, esophagus, and heart, are among the dose-limiting factors for stereotactic body radiation therapy (SBRT) to central lung lesions. The purpose of this study was to characterize the risk of esophagitis for patients treated with SBRT and to develop a statistical dose-response model to assess the equivalent uniform dose (EUD), D10%, D5cc, D1cc, and Dmax dose descriptors of the esophagus for risk of toxicity.
METHODS: Toxicity outcomes of a dose-escalation study of 56 CyberKnife patients from 45 Gy to 60 Gy in three to seven fractions at the Erasmus MC - Daniel den Hoed Cancer Center were utilized to create a probit dose-response model for the esophagus in Dose Volume Histogram (DVH) Evaluator software (DiversiLabs LLC, Huntingdon Valley, PA). All analyses were performed in terms of five-fraction equivalent dosing, using the linear quadratic model with alpha/beta = 3 Gy.
RESULTS: Five grade 2 esophageal complications were reported (Common Terminology Criteria for Adverse Events version 3.0); four were early effects, and one was a late effect. According to our study, D1cc = 32.9 Gy and Dmax = 43.4 Gy corresponded to a complication probability of 50% for grade 2 toxicity. The Radiation herapy Oncology Group 0813 trial initial Dmax limit of 52.5 Gy in five fractions was associated with > 50% risk of grade 2 toxicity in this series, but no grade ≥ 3 esophageal toxicity occurred. Our estimates of esophageal toxicity are compared with the data in the literature and two other published dose-response models.
CONCLUSION: Four articles reported five deaths due to esophageal toxicity; so, our dose escalation began cautiously, and as a result, no grade ≥ 3 esophageal toxicity occurred in our series. Further research needs to be performed to establish more reliable dose limits as longer follow-up and toxicity outcomes are reported in patients treated with SBRT to central lung lesions.
Proceedings of the 98th Annual Meeting of the American Radium Society — americanradiumsociety.org