Background: Osteoradionecrosis (ORN) is a debilitating long-term side effect of radiotherapy (RT) treatment in HNC patients. International incidence rates range from 0.4% to 56%. This is a novel Irish study that assesses ORN incidence rates in HNC patients attending the CUDSH Dental Oncology Unit (2010-2021) and explores potential precipitating factors.
Methods: Retrospective review of 1,050 HNC patients treated in Dental Oncology (2010-2021) identified 47 patients who developed ORN. Their medical, dental and radiotherapy records were retrospectively reviewed; patient, tumour, ORN and treatment-related variables were extracted and analyzed using SPSS and Pearsons Chi-square test.
Results: ORN incidence rate was low (4.4%). Median time to ORN development was 21 months. Seventeen ORN patients received pre-RT mandibular surgery. ORN development in the surgical site was statistically significant (p<.001), at radiation dose ≥ 60 Gy (p=.035), within 12 months of RT treatment (p=.044), due to induced causes (p=.029), and without resolution (p=.019).
Conclusion: Low incidence rates suggest intensive dental intervention is beneficial in reducing ORN risk. Site of pre-RT mandibular bone surgery was a significant risk factor for ORN. These practice changing findings suggest that contouring the bone surgery site and assigning a dose constraint to these areas, where feasible, may minimize ORN risk.