(0694) Osteoradionecrosis Rates Are Low for T3/T4 Oropharyngeal Cancers Whether Treated With Chemoradiation or Primary Surgery

Introduction: While the rates of osteoradionecrosis (ORN) of oropharyngeal cancers (OPSCC) treated with intensity-modulated radiation therapy (IMRT) and proton radiation therapy (PRT) have been documented previously, this outcome for locally advanced disease has not been well quantified. This study aims to characterize the ORN occurrence rates in T3 and T4 OPSCC in surgical/non-surgical IMRT and PRT patients.

Methods: A retrospective single tertiary academic program outcome analysis for development of ORN in those with advanced HPV+ T3/T4 (AJCC 7th Edition) tonsil or base of tongue (BOT) cancer who underwent surgery prior to IMRT and/or PRT with or without chemotherapy from 2010 to 2023 was conducted.

Results: In 122 cases of T3/T4 tonsillar (50%) or BOT (50%) OPSCC, there were 112 males (92%) and 10 females (8%) with a mean age at RT of 60 years (33 to 83 years), of which 78 (64%) received CRT alone; 24 (20%) and 14 (11%) underwent surgery with RT or chemoradiation (CRT), respectively. Just 6 patients (5%) declined radiation. RT was delivered to the primary site and neck. The average dose of RT for non-surgical patients was 70 Gy while the average dose of RT for post-surgical was 61 Gy. Of the sample, 7 patients developed ORN within 37 months. The average RT dose for the 7 (6%) patients was 68 Gy of which 5 were non-surgical CRT.

Conclusions: We report a low rate of ORN among advanced T stage (T3/T4) OPSCC patients undergoing primary chemoradiation or primary surgery followed by adjuvant therapy. Advanced T stage might be expected to be associated with a higher rate of ORN; for example, 17% in a recent analysis of postop PRT treated mixed cohort of T3/T4 OCC/OPSCC patients (Singh, Jama Oto 2023). This is higher than the 4.3% rate of ORN among IMRT patients; however, this study did not specify ORN as a function of T stage (Owosho, Oral Oncology 2017). We observed relatively low rates of ORN in surgical and non-surgically treated locally advanced T-stage patients in our cohort. To discern whether surgery followed by lower dose adjuvant RT might be expected to reduce rates of ORN, larger advanced stage cohorts need to be assessed.