Refining the definition of mandibular osteoradionecrosis in clinical trials: The cancer research UK HOPON trial (Hyperbaric Oxygen for the Prevention of Osteoradionecrosis)

•The classification of mandibular osteoradionecrosis is vague and inconsistent, even in clinical trials.•Here, we explore the definitions of ORN using the blinded clinical outcomes of the HOPON trial.•Minor bone spicules (MBS) <20mm2 are a common outcome, occurring in around 20% of patients in the trial.•Some investigators will report MBS as ORN but others feel this is clinically less important, leading to potential ambiguity.•MBS is worthy of a separate classification in trials addressing the management of ORN.