Simultaneously Integrated Boost Affects Survival in Locally Advanced p16-Negative Oropharyngeal Squamous Cell Carcinoma

Background/Aim: Intensity modulated radiotherapy (IMRT) is the standard of care for oropharyngeal cancer management. IMRT can be applied using either the sequential boost or simultaneous integrated boost (SIB-IMRT) techniques. The purpose of the study was to assess the efficacy of sequential boost technique or SIB-IMRT) in locally advanced p16-negative oropharyngeal squamous cell carcinoma. Patients and Methods: Baseline characteristics and treatment outcomes were compared between patients with locally advanced p16-negative oropharyngeal squamous cell carcinoma, who received sequential RT (n=40) and those who received SIB-IMRT (n=38). Results: In total, 78 patients with locally advanced p16-negative oropharyngeal cancer were identified. Mean age was 63 years. Patients treated with SIB-IMRT had better 5-year overall survival (OS; 78.7% vs. 52.5%, p=0.023) and 5-year disease-free survival (DFS; 87.4% versus 63.5%, p=0.046) compared to sequential group. There was no difference of total severe acute and late toxicity (grade ≥3) incidences. Patients treated with SIB technique had higher rates of mild to moderate late xerostomia (73.7% vs. 52.5%), dysgeusia (63.2% vs. 20%), and dysphagia (44.7% vs. 17.5%). Conclusion: Compared to sequential technique, SIB-IMRT improved both OS and DFS, but higher mild to moderate late toxicity was observed. As long as RT dose constraints to surrounding normal organs can be maintained, SIB technique should be the technique of choice for locally advanced p16-negative oropharyngeal squamous cell carcinoma treatment.