Background: Using high energy X-rays (>10 MV) as a radiotherapy boost in treating oropharyngeal cancers (OPC) to reduce mandible radiation exposure may result in deterioration of disease control rates due to re-build-up of X-rays at the tumor surface. Therefore, we retrospectively compared the treatment outcomes and toxicities in OPC patients treated with radiotherapy using 15 MV and/or 4–6 MV X-rays as a boost. Materials and Methods: Between 2008 and 2014, 63 OPC patients received definitive 3-dimensional conformal radiotherapy. The median total dose was 70.2 (range, 46.8–75.6) Gy. The median follow-up period for surviving patients was 48 (range, 9–88) months. Twenty-one patients (33.3%) received a boost employing 15 MV X-ray in at least one beam during treatment, and 42 patients (66.7%) received only 4–6 MV X-rays. Local control (LC), locoregional control (LRC), disease-free survival (DFS), overall survival (OS) rates and the incidence of osteoradionecrosis (ORN) in the mandible for the two cohorts were estimated using the Kaplan-Meier method and compared using the log-rank test. Results: There were no statistically significant differences between the two cohorts in either treatment outcomes (3-year LC, 81% versus 75% [p=0.742]; 3-year LRC, 71% versus 71% [p=0.925]; 3-year DFS, 66% versus 66% [p=0.934]; 3-year OS, 65% versus 78% [p=0.321]) or incidence of grade >2 ORN in the mandible (9.5% versus 11.9% [p=0.883]). Conclusion: Employing 15 MV X-rays in a boost may provide comparable treatment outcomes to 4–6 MV X-rays. However, reduction in the incidence of ORN in the mandible was not demonstrated.

Background: The optimal radiation dose for oral cavity cancers treated with retrograde superselective intra-arterial chemoradiotherapy (SIACRT) is unclear. The aim of the present study was to evaluate the treatment outcome and toxicity in patients treated with <60 Gy compared with those treated with ≥60 Gy to provide evidence for determining the optimal dose. Materials and Methods: Between January 2009 and December 2013, 159 oral cavity cancer patients were treated with SIACRT with curative intent at a single institution. One hundred and twenty-nine patients received ≥60 Gy and 30 received <60 Gy. Local control (LC), disease-free survival (DFS), overall survival (OS), and toxicity were compared. Propensity score matching was performed to reduce bias. Results: The median follow-up period was 48 months (range, 2–88 months). LC (<60 Gy vs. ≥60 Gy, 81.5% vs. 86.1% at 3 years, p = 0.534), DFS (68.8% vs. 72.4% at 3 years, p = 0.816), and OS (85.9% vs. 72.3% at 3 years, p = 0.132) were comparable between the two groups. There was also no difference in toxicity. However, the median overall treatment period was significantly shorter in the <60 Gy cohort (39 days vs. 49 days, p < 0.0001). Conclusion: The radiation dose may be reduced to <60 Gy when treating oral cavity cancers with SIACRT.