Esophageal tolerance to high-dose stereotactic radiosurgery

Area of Science:

• Oncology
• Radiation Oncology
• Medical Physics

Background:

• Stereotactic radiosurgery (SRS) is increasingly used for spinal metastases.
• Esophageal tolerance is a critical factor in planning SRS for tumors near the esophagus.
• Understanding dose-volume parameters is essential for predicting and preventing esophageal toxicity.

Purpose of the Study:

• To evaluate dose-volume parameters for predicting acute esophageal toxicity in patients with spinal metastasis treated with SRS.
• To identify specific dose-volume thresholds associated with esophageal toxicity.
• To guide safe SRS administration by defining esophageal tolerance limits.

Main Methods:

• Retrospective analysis of 30 cases (27 patients) treated with single-fraction SRS from May 2008 to May 2011.
• Evaluation of esophageal dose-volume histogram parameters including length, volume, maximal dose, and dose-volume thresholds.
• Multivariate analysis to identify predictors of acute esophageal toxicity.

Main Results:

• Six events of grade 1 esophageal toxicity were observed; no higher grades occurred.
• The median time to toxicity onset was 2 weeks (range, 1-12 weeks).
• V15 (volume of the external esophageal surface receiving 15 Gy) significantly predicted acute esophageal toxicity (OR=1.272, p=0.047).

Conclusions:

• V15 of the external esophageal surface is a threshold parameter associated with acute esophageal toxicity after SRS for spinal metastasis.
• Limiting V15 to the external esophageal surface may be a safe and feasible strategy in radiosurgery.
• This finding aids in optimizing SRS planning to minimize esophageal toxicity.