Author(s): Tucker SL, Michalski JM, Bosch WR, Mohan R, Dong L,
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Abstract BACKGROUND AND PURPOSE: For toxicities occurring during the course of radiotherapy, it is conceptually inaccurate to perform normal-tissue complication probability analyses using the complete dose-volume histogram. The goal of this study was to analyze acute rectal toxicity using a novel approach in which the fit of the Lyman-Kutcher-Burman (LKB) model is based on the fractional rectal dose-volume histogram (DVH). MATERIALS AND METHODS: Grade ≥2 acute rectal toxicity was analyzed in 509 patients treated on Radiation Therapy Oncology Group (RTOG) protocol 94-06. These patients had no field reductions or treatment-plan revisions during therapy, allowing the fractional rectal DVH to be estimated from the complete rectal DVH based on the total number of dose fractions delivered. RESULTS: The majority of patients experiencing Grade ≥2 acute rectal toxicity did so before completion of radiotherapy (70/80=88\%). Acute rectal toxicity depends on fractional mean rectal dose, with no significant improvement in the LKB model fit when the volume parameter differs from n=1. The incidence of toxicity was significantly lower for patients who received hormone therapy (P=0.024). CONCLUSIONS: Variations in fractional mean dose explain the differences in incidence of acute rectal toxicity, with no detectable effect seen here for differences in numbers of dose fractions delivered. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
This article was published in Radiother Oncol
and referenced in OMICS Journal of Radiology