Clinical Efficacy and Complications of Intensity-modulated Radiation Therapy in Patients With Oropharyngeal Carcinoma: Especially Focus On Osteoradionecrosis

Abstract

We explored the relative clinical efficacy of intensity-modulated radiation therapy (IMRT) in patients with oropharyngeal cancer (OPC) compared with three-dimensional conformal radiation therapy (3D-CRT). Seventy-four OPC patients treated with definitive IMRT or 3D-CRT between May 2010 and December 2018 were analyzed. Of these, 42 patients were treated with IMRT and 32 with 3D-CRT. We compared clinical benefits and complications. Particular attention was focused on osteoradionecrosis (ORN), which is the most problematic radiation late adverse event, and evaluated the irradiated mandibular volumes. There was no significant difference in the 3-year overall survival (OS), progression free survival (PFS) and locoregional control (LRC) rates between the two groups. However, late Grade 2 xerostomia was lower in the IMRT groups. Four patients (19.0%) developed Grade 3, while no patients developed ORN in the IMRT group (P = 0.003). A comparison of the mandible volumes between the two groups showed that the IMRT group had lower mandibular volumes than the 3D-CRT group in the high-dose range of V40, V50, V60 and V70. In addition, a comparison of the mandibular volumes between ORN and non-ORN showed a significant difference in the V60 and V70. ORN incidence was higher in V60 ≥ 25% and V70 ≥ 15%. A comparison of IMRT and 3D-CRT showed no significant difference in outcomes, however, IMRT led to a significant reduction in late xerostomia and ORN in OPC patients. Reducing of the mandibular V60 and V70 by IMRT seemed to reduce the risk of ORN.