Palliative stereotactic ablative body radiotherapy reirradiation for high volume head and neck cancer

Background: Treatment of advanced head and neck cancer (AHNC) has been a substantial challenge for decades, where approximately 50% of AHNC patients will experience locoregional recurrence or metastatic disease after primary treatment. Surgical resection is the preferred strategy in the setting of locoregional recurrence and is associated with better overall survival (OS) when compared with non-surgical strategies. Here we evaluate the role of stereotatic ablative body radiotherapy (SABR) as a last line strategy for head and neck cancer (HNC) reirradiation. Methods a retrospective review was conducted for HNC patients who underwent reirradiation with SABR from January 2017 to December 2019. All patients were classified as unresectable/inoperable by tumor board and unsuitable to receive chemotherapy due to poor performance status (PS) and/or significant comorbidities. The Kaplan-Meier method was used to estimate locoregional control (LRC), progression free survival (PFS), and overall survival (OS) endpoints. Results Sixty-two patients were eligible for this retrospective analysis. The mean and median gross tumor volume (GTV) were 125.5cc and 75.5cc, respectively. The mean follow up was 9.26 months. The 1- and 2-year OS was 24.0% and 13.3%, respectively, with a median survival time of 6.8 months. The 1-year PFS was 33.6% with a median PFS of 7.7 months. The 1-year LRC was 46.4% with a median LRC of 8.9 months. Univariate and multivariate analysis for PFS demonstrated that mean volume (125.5cc) and an advanced N staging grouping (N ≥ 3) were potential prognostic factors. Three patients developed grade 4 skin necrosis, no other grade 4 toxicity occurred. Conclusion Our data shows that 5-fraction SABR is a promising strategy for last line AHNC reirradiation. Small volumes were strongly associated with overall survival, but even larger tumors can be well controlled. Toxicity seems to be acceptable. Future prospective studies are needed to better understand which patients benefit the most from this treatment. Trial registration: Retrospectively registered.