Background: Mandibular osteoradionecrosis (ORN) is a common toxicity of radiation therapy (RT) in the treatment of oral cavity and oropharyngeal cancers. It consists of progressive bony and mucosal destruction. It is often reported in the native mandible; however, there is a paucity of data on ORN in fibular free flap (FFF) reconstructions exposed to RT after surgery. The purpose of this study is to examine the rate and risk factors for developing ORN in a FFF.
Methods: A retrospective review of patient’s who underwent oral cavity FFF reconstruction followed by RT at the University of Florida was conducted. Data was collected on co-morbid medical conditions, patient demographics, post-operative complications, radiation dosing, concomitant chemotherapy, hardware implanted, tumor staging, and final pathology. Standard comparative statistics were used to compare groups of those who developed FFF ORN and those who did not.
Results: There was no statistically significant baseline differences between patients who developed ORN vs those who did not. The group that went on to develop ORN had a statistically significant (p=0.02) higher average dose of radiation at 69 Gy compared to 54 Gy in the non-ORN group but no appreciable difference in fraction size (1.83 vs 1.91). All patients in the ORN group received a total radiation dose of 60 Gy or greater compared to 60% in the non-ORN group (p=0.05). There was a highly significant difference (p=0.005) between the number of patients receiving concomitant chemotherapy with their RT, 80% in the ORN group vs. 20% in the Non-ORN group. The patients in the ORN group were found to have an average of 1.40 years to diagnosis of ORN following completion or RT.
Conclusion: Patients who develop FFF ORN do so in a similar time frame as those with mandibular ORN. Concomitant chemotherapy and higher doses of RT (above 66 Gy) increase the risk of developing developing FFF ORN.