Two-step Intensity-modulated Radiation Therapy for Oropharyngeal Cancer: Initial Clinical Experience and Validation of Clinical Staging

Abstract

Aim: To evaluate the clinical results of two-step intensity-modulated radiation therapy (IMRT) for oropharyngeal cancer. Patients and Methods: Eighty patients were treated with two-step IMRT between 2002 and 2014. Whole-neck radiotherapy (44.0-50.0 Gy/22-25 fractions) was delivered by IMRT, followed by boost IMRT to the high-risk clinical target volume (total dose of 70.0 Gy/35 fractions). Forty-seven patients received concurrent chemotherapy. Immunohistochemistry for human papillomavirus type 16 (HPV/p16) was performed for 64 patients. Results: The 5-year overall survival and locoregional control rates for stage I, II, III, and IVA-B disease were 80.0%, 75.0%, 78.0%, and 64.0% and 100.0%, 75.0%, 92.0%, and 82.0%, respectively. Overall survival was significantly higher in HPV/p16-positive patients than in HPV/p16-negative patients (p=0.01). Xerostomia of grade 2 or more was noted in 10 patients. Conclusion: Favourable overall survival and locoregional control rates with excellent salivary preservation were obtained using the two-step IMRT method for oropharyngeal cancer.