Safety / Regulatory
2026-08-10 ASCO Genitourinary Cancers Symposium 2022
Organs at Risk Radiation Dose Constraints: 2025 Update
TL;DRSFRO 2025 OAR dose-constraint update: normofractionated, moderate hypofractionated and ablative tables across skull base, H&N, lung, breast, oesophagus, liver.
START BFAST-FORWARDRTCMIENDOMETRE
The practical shift is coverage of ablative regimens per fraction number (1, 3, 4, 5, 8) alongside normofractionation, plus cardiac substructures (LAD, left ventricle) and a proposed dorsal vagal complex OAR. Numbers are tiered optimal vs mandatory, so a plan that exceeds an optimal value is a documented conversation, not a violation.
Practical shift is the per-fraction-number ablative columns (1, 3, 4, 5, 8) sitting alongside normofractionation in one grid, plus cardiac substructures (LAD, left ventricle) as constrained organs. The optimal versus mandatory tiering is what changes planning behaviour: it names which values are negotiable against target coverage.
12 details
SFRO consensus update, part of the RecoRad 4th edition, covering adult external beam radiotherapy and brachytherapy practice. Constraints were compiled from international consensus guidelines and clinical trial data, then validated by national reference experts rather than derived from a new dataset.
Tables are indexed by tumour site and by fractionation: normofractionation, moderate hypofractionation, accelerated hyperfractionation (lung), and ablative regimens split by fraction number (1, 3, 4, 5, 8). Dmax is approximated by D2 % in normofractionation and D0.035 cm3 in stereotactic plans; several hypofractionated entries are given as EQD2.
No clinical endpoint. The deliverable is a set of dose-volume objectives intended for direct implementation into treatment planning systems as standardized clinical objectives.
Constraints are tiered as optimal versus mandatory, with ALARA used where no numeric threshold is offered (parotid in the brain table, lacrymal gland under moderate hypofractionation). The authors require that pts be informed of the risk when a constraint is exceeded.
Breast constraints are anchored to the schedules of START B (40 Gy in 15) and FAST-FORWARD (26 Gy in 5); liver constraints are built on the ASTRO clinical practice guideline across 3, 5 and ≥ 20 fractions. This is a national harmonization layer over those sources, not a competing evidence synthesis.
The authors state most constraints still rest on 3D conformal-era data, which sits awkwardly with IMRT's larger low-dose bath and with ablative dose gradients. Biological modifiers of risk (individual radiosensitivity, genomic profile, concurrent immunotherapy) are not accounted for, and dose to immune organs at risk is named as unresolved.
The value here is harmonization, not novelty: the stated problem is the multiplicity of circulating constraint sets and the absence of a single reference. The optimal/mandatory tiering is the part that changes daily behaviour, because it tells a planner which values are negotiable against target coverage and which are not.
- Validity of 3D conformal-derived constraints under IMRT and SBRT
- Dose thresholds for immune organs at risk with concurrent immunotherapy
- Dorsal vagal complex as an OAR for radiation-induced nausea