Treatment outcomes of the patient with sinonasal mucosal melanoma: the role of endoscopic resection and postoperative radiotherapy

Background The standard of care for sinonasal mucosal melanoma is surgery and postoperative radiotherapy (PORT). Our treatment strategy comprises endoscopic resection and PORT. We performed combined endoscopic and open resection or applied an external approach alone when sufficient resection was difficult to achieve endoscopically. The objective of this study was to evaluate the validity of our treatment strategy. Methods We assessed 30 patients with sinonasal mucosal melanoma who underwent definitive therapy between January 2002 and April 2021, and conducted a retrospective analysis. The median follow-up period was 2.2 years. The primary endpoint was overall survival. The Kaplan–Meier method was used for the calculation of survival rates, the cumulative incidence of distant metastasis, and local recurrence. Results Twenty-eight patients underwent surgery. The other two patients were treated by definitive proton beam therapy. Twenty-one of 28 (75%) patients underwent resection by endoscopic approach alone. Postoperative radiotherapy was performed for all 28 patients who underwent surgery. Twenty-one patients (70%) experienced recurrence during the observation period. Overall, distant metastasis was observed in 19 patients. Twelve patients died during the observation period, with 10 of the 12 patients (83%) dying of distant metastasis. The overall survival rate at 2 and 5 years was 70% and 46%, respectively. The cumulative incidence rate of distant metastasis at 2 years was 63%, while the 2-year cumulative incidence rate of local recurrence was 6.7%. Conclusion The local disease was controlled by our treatment strategy. To improve treatment outcomes, control of the distant metastasis is needed.