Tumor Size Changes after Neoadjuvant Systemic Therapy for Advanced Oropharyngeal Squamous Cell Carcinoma

Objective: In this study, we assessed tumor size changes after neoadjuvant systemic treatment in patients with advanced oropharyngeal squamous cell carcinoma (OSCC).Materials and methods: Primary objective of this study was to assess tumor size changes after neoadjuvant systemic treatment in patients with advanced OSCC.For this purpose, advanced OSCC patients with available imaging data as part of initial workup were studied.All included patients received upfront neoadjuvant systemic treatment and then were referred for radiation therapy (RT) at Department of Radiation Oncology at Gulhane Medical Faculty, University of Health Sciences.We have performed a comparative analysis for tumor sizes at diagnostic CT scan of the patients and at CT-simulation for radiation treatment planning after neoadjuvant systemic treatment.CTsimulations of the patients have been performed at CT-simulator (GE Lightspeed RT, GE Healthcare, Chalfont St. Giles, UK) available at our institution.Tumor size changes after neoadjuvant systemic treatment was documented for comparative evaluation.Results: As the main result of our study, we found a mean decrease of 35% in tumor size after neoadjuvant systemic treatment for patients with advanced OSCC.Conclusion: Our results may have implications for implementation of adaptive RT strategies despite the need for further supporting evidence.