Long term outcome and late toxicity Of SIB-IMRT in definitive management of head and neck cancers in patients not suitable for chemo-radiotherapy.

Objective: To evaluate efficacy and late toxicity of intensity-modulated radiotherapy with simultaneous integrated boost (IMRT-SIB) in definitive management of head-and-neck cancers. Methods: In this prospective interventional study, histological proven squamous cell carcinoma of oropharynx, hypopharynx, or larynx with stage T1-3 N0-3 M0 who were not candidates for concurrent chemotherapy were treated with IMRT-SIB with radical intent. Doses prescribed for IMRT-SIB to meet the clinical needs of nodal volumes were either SIB-66 schedule 66 Gray (Gy) prescribed to high risk (HR) planned target volume (PTV), 60 (Gy) to intermediate risk (IR) PTV and 54 Gy to low risk (LR) PTV in 30 fractions or SIB-70 schedule 70 Gy to PTV-HR, 59.4 Gy to PTV-IR and 56 Gy to PTV-LR in 33 fractions. Result: Forty-five patients were included. Forty-two patients were treated with SIB-66 schedule and three patients with SIB-70 schedule. The median follow-up period was 21 (6-68) months. There was residual disease in three patients. Recurrence was observed in 24 patients. Most recurrences were in HR volume (n = 19) and three patients had distant failure. Estimated 2-year locoregional control, disease-free survival, and overall survival were 55.55%, 49.7%, and 51.1%, respectively. Grade 3 late skin toxicity, subcutaneous fibrosis, and xerostomia were observed in three patients. Conclusions: Efficacy and late toxicity of IMRT-SIB observed in our study suggest it as a suitable treatment option for patients who are not fit for chemoradiation.