A retrospective study on unresectable or inoperable head and neck cancers treated with stereotactic ablative brachytherapy

Purpose
The aim of the present study was to assess the clinical efficacy and safety of stereotactic ablative brachytherapy (SABT) for unresectable or inoperable head and neck cancers.

Material and methods
This study retrospectively assessed clinical data of 37 patients with unresectable or inoperable head and neck cancers treated with SABT from October 2016 to October 2021. Variables evaluated included local efficacy, local control rate (LCR), overall survival (OS) rate, and radiological adverse effects.

Results
The median follow-up was of 34 months (range, 5-59 months), and LCR at 6, 12, and 24 months was 89.2%, 78.2%, and 69.4%, respectively. The median survival time was 16 months [95% confidence interval (CI): 10.5-21.5 months], and the OS rate at 6, 12, and 24 months was 97.3%, 70.3%, and 34.5%, respectively. The results of univariate analysis revealed that the type of pathology and gross tumor volume (GTV) D90 were related to LCR (p < 0.05). However, the type of pathology, GTV D90, age, and implantation site were related to OS rate (p < 0.05). The results of multivariate analysis showed that the type of pathology and GTV D90 were substantially related to LCR and OS rate (p < 0.05). The evaluation of post-operative radiological adverse reactions revealed that seven cases (18.9%) developed grade 1-2 skin reactions, four cases (10.8%) developed grade 1-2 oral mucosal outcomes, and no cases developed grade 3 or higher adverse reactions. Post-operative seed dislocation occurred in three patients with tongue cancer.

Conclusions
SABT has produced good local control and mild adverse reactions in the treatment of unresectable or inoperable head and neck cancers. Additionally, it is safe, feasible, minimally invasive, and has fewer adverse effects than other treatment modalities.