Incidence of Osteoradionecrosis with Concurrent Oral Bisphosphonate Therapy

Head and neck radiotherapy (HNRT) for oropharyngeal cancer has been reported to result in a 5-15% incidence of osteoradionecrosis (ORN). Oral bisphosphonate therapy (OBT), prescribed for osteoporosis, has been implicated in the development of osteonecrosis of the jaws (ONJ). The incidence of OBT-induced ONJ has not been definitively determined. Objectives: This study examined whether concomitant use of OBT with HNRT increased the risk of ORN. Methods: Medical and dental records were reviewed in HNRT patients (n=368; 280 male, 88 female) treated at the University of Florida between 1990 and 2006. All patients received definitive HNRT for cancer of the base of tongue, tonsil, soft palate, nasopharynx, or pharyngeal wall. Patients irradiated using IMRT were excluded from the study. OBT prior to initiation of HNRT and incidence of ORN were recorded and statistically analyzed using a chi-square test. Results: The overall incidence of OBT was 2.2%. None of the OBT patients in the study received adjuvant chemotherapy. Overall, 31% of the non-OBT patients received chemotherapy, while 27% of the non-OBT/ORN patients received chemotherapy. The mean dose of HNRT (7430 cGy) was the same in OBT and non-OBT groups. The overall incidence of ORN was 12.0%. The incidence of ORN among non-OBT patients (n=360) was 10.8% with a mean onset time of 34.4 months after HNRT. The incidence of ORN among OBT patients (n=8) was 62.5% with a mean onset time of 10.5 months after HNRT. The results of the chi-square test [Χ²(1)=19.846,p.<.001] indicate that significantly more patients who received OBT developed ORN than non-OBT patients. Conclusion: Patients taking OBT prior to the initiation of HNRT have a significantly higher risk of developing ORN, possibly with earlier onset, than non-OBT patients. Oral bisphosphonates are a risk factor for the development of ORN. This research was supported by UFCD Student Summer Research Fellowship.