2856 - Predictors of Osteoradionecrosis following Post-Operative Intensity-Modulated Radiation Therapy and Proton Therapy for Oral Cavity Cancer
Presenter(s)
T. Treechairusame1,2, A. Singh3, E. C. Dee1, J. H. Oh4, P. Zhang4, J. Xiong4, E. Aliotta4, A. H. Safavi1, Y. Wu1, C. Caineng1, D. Gelblum1, E. Sherman5, J. Huryn3, S. Yom3, I. Ganly3, J. Cracchiolo3, M. Cohen3, R. J. Wong3, C. Estilo3, and N. Y. Lee1; 1Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, 2Division of Radiation Oncology, Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, 3Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, 4Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, 5Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
Purpose/Objective(s):
To report the prevalence of osteoradionecrosis (ORN) in a uniform cohort of postoperative oral cavity cancer (OC) treated either with intensity-modulated radiotherapy (IMRT) or proton therapy.Materials/Methods:
A total of 479 consecutive patients (426 with IMRT and 53 with proton therapy) between 2013 and 2023 were included in this analysis from an institutional OC database (N=911). Patients who developed ORN were identified and uniformly graded using Common Terminology Criteria for Adverse Events (V5.0) adapted for radiation associated ORN. Kaplan-Meier method was used to estimate the cumulative incidence of ORN. Cox proportional hazards regression models were performed to identify predictors of ORN.Results:
The overall ORN prevalence for each grade was 11% (47/426) in IMRT (21 grade 1, 13 grade 2, 13 grade 3) vs 11.3% (6/53) in proton therapy (2 grade 1, 3 grade 2, 1 grade 3). The median time to develop ORN was 13 months (IQR, 9-39 months) and 29 months (IQR, 4-42 months) for those treated with IMRT and proton therapy, respectively. There was no statistically significant difference in radiation modality between IMRT and proton therapy in univariate analysis [Hazard ratio (HR) 1.29 (0.55 - 3.05), P=0.551]. On univariate analysis, smoking history (P=0.072), tumor stage (P=0.011), tumor with mandibular bone invasion (P=0.007), and the extent of mandibular resection (P<0.001) were correlated with ORN development. On multivariate analysis, only the extent of mandibular resection was found to be significantly associated with ORN development with a HR of 3.32 (1.78-6.19), P < 0.001. Patients who developed ORN had a higher overlapping area between planning target volume and mandible (25.2 cc vs. 17.3 cc, P < 0.001) from IMRT group and mandible V6000cGy (36% vs. 27.8%, P = 0.002).Conclusion:
The prevalence of ORN is similar following post-operative IMRT and proton therapy for OC in a consecutive and uniform cohort of patients. The extent of surgical resection of a mandible was identified as a significant predictor of ORN.