ASTROnews: ASTRO publishes supplement studying normal tissue effects
By Barbara Muth, Director of Research
QUANTEC, or the Quantitative Analysis of Normal Tissue Effects in the Clinic, is the result of a three-year effort to review dose, volume and outcome data for different organs with an eye toward determining acceptable dose volume constraints for treatment planning. The results were published in a March supplement to the International Journal of Radiation Oncology*Biology*Physics, with introductory papers, 16 organ-specific clinical papers and a series of vision papers that identify issues in need of further study. The initiative to produce these papers started with a workshop in 2007.
The authors of these papers—radiation oncologists, physicists and statisticians—committed a significant amount of time to reviewing the literature and discussing their reviews, meeting every Tuesday afternoon by conference call for more than two years. A steering committee of eight, Søren Bentzen, Ph.D., D.Sc., Louis S. Constine, M.D., Joseph O. Deasy, Ph.D., Avi Eisbruch, M.D., Andrew Jackson, Ph.D., Lawrence B. Marks, M.D., Randall Ten Haken, Ph.D., and Ellen D. Yorke, Ph.D., led the effort.
The organ-specific papers cover the brain, the optic nerve and chiasm, the brain stem, the spinal cord, the ear, the parotid, the larynx and pharynx, the lung, the heart, the esophagus, the liver, the stomach and small bowel, the kidney, the bladder, the rectum, and the penile bulb. Within each of these papers, there are 10 sections. The Clinical Significance section describes situations when the organ is likely to be irradiated and the incidence and significance of organ injury when that occurs. The Endpoints section of each paper describes the endpoints usually considered when assessing an injury, the impact of the selected endpoints on reported injury rates, the challenges and utilities of different endpoints and the time course of the organ injury. In the section on Challenges Defining Volumes, the authors describe how the organ is typically segmented on treatment planning images. This section includes a discussion of the uncertainties in organ definition and the associated impact on DVHs and on dose/volume/outcome analyses. The Review of Dose/Volume Data provides the reader with a summary of reported 3-D dose/volume data for clinically-relevant outcomes. Factors Affecting Risk describes the other factors associated with the risk of injury. In Mathematical/Biological Models, the models used to relate 3-D dose/volume data to clinical outcomes are summarized. Model parameters, limitations and uncertainties are also described. The Special Situations section addresses situations in which the presented conventional fractionation data/models may not apply. In Recommended Dose/Volume Limits, the available information has been condensed into meaningful dose/volume limits, together with associated risk rates. Future Toxicity Studies identifies the areas in need of further study. Toxicity Scoring provides the reader with recommendations for how to score organ injuries.
Future plans for this data include the possibility of an online database to facilitate updating the information, posting updated reviews on an ASTRO Web page and, perhaps, the development of handheld tools to facilitate dose planning in the clinic. You can view the supplement online at www.redjournal.org.