Long-term treatment outcomes and prognosis of mucosal melanoma of the head and neck: 161 cases from a single institution

Objectives: This study aimed to evaluate the clinical features, treatment outcomes and prognostic factors of mucosal melanoma of the head and neck (MMHN) in patients who were treated at our institution. Materials and methods: Between Jan. 1981 and Oct. 2015, 161 patients with non-metastatic MMHN were treated at our institution. The patients' clinical characteristics, treatment modalities, outcomes, prognostic factors, and failure patterns were retrospectively analysed. Results: With a median follow-up time of 74 months, the 5-year overall survival rate (OS), local control rate (LC), distant metastasis-free survival (DMFS) were 44.4%, 59.4%, and 49.3%, respectively. Regarding the different treatment modalities, the 5-year OS was 50.0% in the surgery group and 43.1% in the surgery combined with radiotherapy group, while, the 5-year LC rate was 42.5% in the surgery group and 75.3% in the surgery combined with radiotherapy (p < 0.001). According to the AJCC 7th edition staging system for MMHN, the 5-year OS for patients with stage III, stage IVA, and stage IVB MMHN were 65.2%, 33.1% and 14.3%, respectively (p < 0.001). In the multivariate analysis, the T stage, neck lymph node involvement, and surgical margins were independent prognostic factors for OS; surgical margins and adjuvant radiotherapy were independent prognostic factors for LC. Conclusion: The addition of radiotherapy improves the local control rate of MMHN. T stage, neck lymph node status, and surgical margins are independent prognostic factors for the OS in patients with MMHN. The AJCC 7th edition staging system for MMHN appears to effectively stage this disease.