WE-F-304-05: Cranial TCP/NTCP Modeling Insights and Caveats

Authors


Abstract

Stereotactic Body Radiation Therapy (SBRT) was introduced clinically more than twenty years ago, and many subsequent publications have reported safety and efficacy data. The AAPM Working Group on Biological Effects of Hypofractionated Radiotherapy/SBRT (WGSBRT) extracted published treatment outcomes data from extensive literature searches to summarize and construct tumor control probability (TCP) and normal tissue complication probability (NTCP) models for six anatomical regions: Cranial, Head and Neck, Thoracic, Abdominal, Pelvic, and Spinal. In this session, we present the WGSBRT's work for cranial sites, and recurrent head and neck cancer. From literature-based data and associated models, guidelines to aid with safe and effective hypofractionated radiotherapy treatment are being determined. Further, the ability of existing and proposed radiobiological models to fit these data is considered as to the ability to distinguish between the linear-quadratic and alternative radiobiological models such as secondary cell death from vascular damage, immunogenic, or bystander effects. Where appropriate, specific model parameters are estimated. As described in “The lessons of QUANTEC,” (1), lack of adequate reporting standards continues to limit the amount of useful quantitative information that can be extracted from peer-reviewed publications. Recommendations regarding reporting standards are considered, to enable such reviews to achieve more complete characterization of clinical outcomes.

1 Jackson A, Marks LB, Bentzen SM, Eisbruch A, Yorke ED, Ten Haken RK, Constine LS, Deasy JO. The lessons of QUANTEC: recommendations for reporting and gathering data on dose-volume dependencies of treatment outcome. Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3 Suppl):S155–60.

Learning Objectives:

  • 1.Describe the techniques, types of cancer and dose schedules used in treating recurrent H&N cancers with SBRT
  • 2.List the radiobiological models that compete with the linear-quadratic model in explaining the results of hypofractionated RT
  • 3.Describe the dose/volume metrics that are considered safe in SBRT treatment of tumors near the optic structures.
  • 4.Discuss the efficacy of hypofractionation and dosing schedules used in treating vestibular schwannomas
  • 5.Identify some difficulties in modeling TCP and NTCP for cranial tumors treated with hypofractionation.

One moderator, Dr. Grimm, designed and holds intellectual property rights to the DVH Evaluator software tool which is an FDA-cleared product in commercial use, and can analyze some of this data.

No others have relevant conflicts of interest.

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