Salvage brachytherapy with or without external beam radiotherapy for oral or oropharyngeal squamous cell carcinomas in previously irradiated areas: carcinologic and toxicity outcomes of 25 patients

Introduction
The aim of this study was to assess outcomes of salvage brachytherapy for oral and oropharyngeal squamous cell carcinoma in previously irradiated areas.

Material and methods
This was a retrospective study with 25 patients, treated between 1997 and 2016 for primary (21 cases) or recurrent (4 cases) oral or oropharyngeal squamous cell carcinomas in previously irradiated areas. Fifteen patients were treated with salvage brachytherapy (BT) alone, while 10 patients additionally received external beam radiotherapy (EBRT). Median BT dose was 45 Gy (range, 15-64 Gy), and a median total cumulative dose was 57 Gy (range, 40-70 Gy). Patient age, tumor stage, radiotherapy dose, and time between first treatment and recurrence were analyzed as prognostic factors.

Results
Median overall survival (OS) was 16 months. Patients with less advanced (T1) tumors survived significantly longer (27 vs. 14.5 months, p = 0.046). Five patients experienced a local recurrence, and only one of them was treated with a total dose greater than 60 Gy. In multivariate analysis, patients with T1 lesions had a significant higher OS rate compared to patients with larger lesions (HR = 6.25, 95% CI: 1.18-33.1%, p = 0.031). Patients who received more than 60 Gy had a non-significant, 80% increased OS than those treated with a lower dose (p = 0.072). There was four grade 3 acute toxicities, and no grade 3 or more late toxicities.

Conclusions
Multimodal treatment, including salvage BT, may offer a curative option for selected patients with an acceptable risk of severe toxicity for the treatment of primary or recurrent tumors in previously irradiated areas.