Stereotactic ablative radiotherapy (SABR) for recurrent and previously irradiated head and neck cancers

OBJECTIVE: To assess the response and toxicity of stereotactic ablative radiotherapy (SABR) in patients with recurrent head and neck cancer (HNC), who had previously received radiation for their primary tumor. METHODS: Between 2014 and 2018, patients who received SABR to recurrent HNC within the previously irradiated region were retrospectively reviewed. Mean age was 60 years (range 30–78 Years). Histology was confirmed in all patients. MRI and /or CT-positron emission tomography were done to evaluate local extent and to rule out metastasis. Response was assessed as per RECIST/PERCIST Criteria. Cox proportional hazards regression and the Kaplan–Meier methods were used for statistical analysis. RESULTS: 32 patients received SABR. RPA Class II, III patients were 20 and 12 respectively. 87% patients received a dose of ≥30 Gy/5 fractions. Median follow-up was 12 months. Estimated 1 year and 2 years local control was 64.2 and 32% and 1 year and 2 years overall survival was 67.5 and 39.5% respectively. Acute Grade 2 skin and Grade 3 mucosal toxicity was seen in 31.3 and 28% patients respectively. Late Grade 3 toxicity was seen in 9.3% patients. CONCLUSION: Re-irradiation with SABR yields high local control rates and is well tolerated. It compares favorably with other treatment modalities offered to patients with recurrent HNC. It is also suitable for patients of RPA Class II and III. There is need for novel systemic agents to further improve the survival. ADVANCES IN KNOWLEDGE: Treatment of patients with recurrent HNC is challenging and is more difficult in previously radiated patient. More than 50% patients are unresectable. Other options of salvage treatment like re-irradiation and chemotherapy are associated with poor response rates and high incidence of acute and late toxicity (Gr ≥3 toxicity 50–70%). SABR is a novel technology to deliver high dose of radiation to recurrent tumor with high precision. It yields high local control rates with less toxicity compared to conventionally fractionated radiation.