Efficacy of surgery combined with postoperative I interstitial brachytherapy for treatment of acinic cell carcinoma of the parotid gland in children and adolescents.

Background: Acinic cell carcinoma (AciCC) is rare in children; therefore, reaching a consensus on its management is challenging and radiotherapy is limited by concerns about long-term toxicity. The purpose of this study is to analyze the effectiveness and safety of surgery plus postoperative I interstitial brachytherapy (IBT) for children and adolescents with AciCC of the parotid gland (PG) treated at a single institution.

Procedure: Sixteen patients ≤ 18 years old with AciCC of the PG treated with surgery plus I IBT from 2007 to 2018 were included. Surgery was the primary treatment; ten patients underwent total gross excision and six subtotal gross excision. The matched peripheral dose was 60-120 Gy. Overall survival, disease-free survival (DFS), local control rate, distant metastasis, and radiation-associated toxicities were analyzed, and factors influencing outcomes were evaluated.

Results: During follow-up (1.8-12.6 years; mean, 6.3 years), lymph node metastasis was observed in one case, 2.6 years after I IBT treatment. The five-year overall and DFS rates were 100% and 91.7%, respectively. On univariate analysis, tumor size ≥ 3 cm (100% vs 50%; P = 0.025) and extraglandular extension (100% vs 50%; P = 0.025) were significant prognostic indicators for DFS. No severe radiation-associated complications occurred.

Conclusions: Children and adolescents with AciCC of the PG with high-risk features can be managed using surgery plus postoperative I IBT with excellent local control. Radiation-related complications were minor. Patients with facial nerve involvement can have their facial nerves preserved. Residual tumors can be safely managed using adjuvant I IBT.