for Sinonasal Mucosal Melanoma: A Single-Institution Retrospective Experience

Background: Mucosal melanoma (MM) is a rare disease associated with poor prognosis. 5-year overall survival rate is typically ~35%. Such poor prognosis is often contributed to early distant metastases soon after diagnosis or high locoregional recurrence following initial treatments, making the management of mucosal melanoma difficult. Wide surgical excision with the goal of achieving negative margins is mainstay treatment. However, achieving clear margins for sinonasal tumors is difficult due to anatomic and functional considerations. Adjuvant radiotherapy can improve local control, but is limited by critical radiosensitive structures surrounding nasal and paranasal sinuses tumors. Use of modern radiotherapy techniques like intensity-modulated radiotherapy (IMRT) can deliver high doses of radiation while minimizing radiation to critical structures. We report the clinical outcomes of patients with sinonasal MM treated with adjuvant IMRT.

Methods: We identified patients with biopsy and histologically proven sinonasal MM undergoing adjuvant IMRT for curative intent between 2005 and 2015 at a single institution. Median treatment dose was 66 Gy (range, 50–70.2 Gy) in 1.8 to 2 Gy daily fractions to site of primary disease. Patterns of survival, disease control, and toxicity were assessed. Kaplan-Meier method was used to assess time to treatment failure and death.

Results: A total of 18 patients were identified. Seven patients had incomplete records and 1 patient was treated for palliative intent, and were not included in the analysis. Of the 10 remaining patients, median age was age was 69 (range, 55–79) and median follow-up was 16 months (range, 0.92–111). 60% were female, and 90% were Caucasian. 80% of patients had ECOG performance status of zero or one. The proportion of patients with T3, T4a, and T4b disease were 40%, 40%, and 20%. Nine of 10 patients were treated for primary disease, and one was treated for recurrence. Eight of 10 patients achieved negative margins from surgical resection, and two patients had positive margins. Three patients were treated with immunotherapy and one with chemotherapy for developing distant metastasis after adjuvant radiation. Eight patients had no evidence of disease, one had a partial response, and one had stable disease after adjuvant radiation. Three patients had local recurrence and four patients developed distant metastases. 3- and 5-year overall survival rates were 80.8% and 60.6%. 3-year local disease-free survival (DFS) was 77.8%, with median time to failure of 29.9 months (range, 0.75–95). 3-year distant DFS was 66.7%. Median time to distant failure was 6.6 months (range, 0.66–96). Treatment-related toxicities were mild and well tolerated. There were 18 grade 1 reactions including fatigue, xerostomia, dysgeusia, and mucositis and two patients with reversible visual changes (blurry vision and mild optic neuritis).

Conclusion: IMRT following aggressive surgical resection improves local tumor control and yields favorable survival outcomes with minimal toxicities in appropriately selected patients. Further research is needed to confirm these findings.