Osteoradionecrosis as a complication following post-operative intensity-modulated radiation therapy or proton therapy for oral cavity cancer

Abstract

Objective: To report the prevalence of osteoradionecrosis (ORN) in oral cavity (OC) cancer patients following intensity-modulation radiation therapy (IMRT) or proton therapy (PRT). Methods: A retrospective study was conducted on consecutive cohort of OC cancer patients treated with IMRT or PRT for squamous cell carcinoma (SCC). Patient information and treatment related variables were collected from medical records. Patients who developed ORN were uniformly graded using CTCAE v5. Cox proportional hazards model was used to compare risk factors between IMRT and PRT. Kaplan-Meier method was used to estimate the cumulative incidence (CI) of ORN. Results: A total of 479 OC SCC patients (426 treated with IMRT and 53 treated with PRT) were included in this study. The median follow-up time was 35 months (IQR, 17–68 months). The prevalence of ORN was similar between groups: 11% (47/426) in the IMRT group (21 Grade 1, 13 Grade 2, 13 Grade 3) and 11.3% (6/53) in the PRT group (2 Grade 1, 3 Grade 2, 1 Grade 3). The median time to ORN development was shorter following IMRT [13 months (IQR, 9–39)] compared to PRT [28 months (IQR, 4–42)].The 3-year CI of any grade ORN was 9.6 % and 11.4 % for IMRT and PRT (log-rank P-value = 0.550), respectively. On univariable analysis, smoking history (P = 0.072), tumor stage (P = 0.011), tumor with mandibular invasion (P = 0.007), and extent of mandibular intervention (P < 0.001) was associated with ORN development. On multivariable analysis, the extent of mandibular intervention remained a significant risk factor (P < 0.001). Conclusion: In this single-institution study, we found a similar prevalence of ORN following IMRT (11%) and PRT (11.3 %) in OC cancer patients.