Table 1.
Dose-volume relationships ca. 1990 and 2009+
| ca. 1990 | 2009+ |
|---|---|
| Treatment usually with parallel opposing fields or “box” techniques – 3DCRT gaining ground clinically in some centers | Widespread use of conformal techniques, including IMRT – often resulting in highly non-uniform dose distribution in organs at risk with large volumes receiving low doses |
| RT typically delivered as single-modality–spectrum of toxicities relatively well characterized | Many curative cases receiving combined modality therapy – many regimens are very toxic leading to problems with compliance |
| Conventional fractionation dominates – clinical trials of hyperfractionation and accelerated fractionation | Conventional fractionation dominates – clinical trials of hypofractionation in progress |
| Authors search for a “safe” dose-volume constraint | Increasing appreciation of the risk-benefit trade-off in an individual patient – a monotonic increase in toxicity risk with increasing dose/increasing volume |
| Early interest in NTCP modeling – Lyman model most widely used | Change from “more models” to “more data” – Lyman model still widely used, but new modeling strategies are being pursued |
| Analysis often based on groups of patients | Analysis of individual patient level data |
| Lack of consistency in contouring organs at risk among investigators | Lack of consistency in contouring organs at risk among investigators |
| Models often applied with parameters from the literature – no adjustment for patient or treatment characteristics | Statistical estimation of model parameters – often with adjustment for significant patient or treatment characteristics |
| Toxicity under-scored and under-reported in most studies | Toxicity under-scored and under-reported in most studies – despite attempts to define dictionaries for toxicity reporting such as CTCAE |
| A lack of quantitative, evidence-based dose-volume constraints – Emami et al. develops a ground-breaking set of consensus constraints for partial organ irradiation | A lack of quantitative, evidence-based dose-volume constraints – the QUANTEC group initiates a series of systematic literature reviews |