2026 AAMP Annual Scientific Session: New Classification of ORN / Tools for Interdisciplinary Diagnosis

New Classification of Osteoradionecrosis / Tools for Interdisciplinary Diagnosis C. David Fuller, MD, PhD — UT MD Anderson Cancer CenterModern radiotherapy has steadily improved head and neck cancer survival, shifting the clinical challenge toward survivorship; two-thirds of long-term survivors carry at least one moderate-to-severe toxicity. Osteoradionecrosis of the jaw (ORN) remains among the most consequential: it persists despite IMRT, its biology is incompletely explained by the classic Marx hypoxic-hypocellular-hypovascular and Delanian fibroatrophic models, no treatment is universally effective, and the economic burden runs from thousands of dollars for conservative care to roughly $170,000 for advanced surgical reconstruction. The mandible carries roughly six-fold higher risk than the maxilla owing to its single-vessel supply and dense cortical architecture.Progress has been hampered by definitional chaos: more than nine competing definitions, sixteen grading systems, and no dedicated ICD-10 code. The talk presents the response. The 2024 ISOO-MASCC-ASCO guideline provides an operational definition (radiographic lytic/sclerotic change, exposed bone, or bone probed through a fistula within an irradiated field). The ClinRad system (Watson et al., JCO 2024) stages ORN from minor bone spicules through Stage 0 (radiographic-only alveolar change) to Stage 3 (pathologic fracture or fistula), outperforming legacy systems and newly capturing maxillary and radiographic-only disease. A 69-expert ORAL Consortium Delphi study established consensus definitions and nine minimum data elements, while also exposing specialty-dependent “knowledge silos” in case staging.Diagnostic tools follow. A blinded interobserver study showed neither CT nor panoramic radiography alone suffices, but paired 2D/3D imaging raises AUC to 0.79–0.98 across specialties—though inter-rater agreement for ClinRad staging remains slight and confidence does not track accuracy. Quantitative approaches address this gap: voxel-level Hounsfield analysis (AUC 0.87), CT radiomics, DCE-MRI vascular biomarkers (Ktrans, Ve) with an FDA Biomarker Qualification letter of support, and black-bone/UTE MRI morphometry.