Trends in Incidence and Survival of 1496 Patients with Mucosal Melanoma in The Netherlands (1990-2019).

Background: Mucosal melanoma (MM) is a rare tumour with a poor prognosis. Over the years, immune and targeted therapy have become available and have improved overall survival (OS) for patients with advanced cutaneous melanoma (CM). This study aimed to assess trends in the incidence and survival of MM in the Netherlands against the background of new effective treatments that became available for advanced melanoma.

Methods: We obtained information on patients diagnosed with MM during 1990-2019 from the Netherlands Cancer Registry. The age-standardized incidence rate and estimated annual percentage change (EAPC) were calculated over the total study period. OS was calculated using the Kaplan-Meier method. Independent predictors for OS were assessed by applying multivariable Cox proportional hazards regression models.

Results: In total, 1496 patients were diagnosed with MM during 1990-2019, mostly in the female genital tract (43%) and the head and neck region (34%). The majority presented with local or locally advanced disease (66%). The incidence remained stable over time (EAPC 3.0%, = 0.4). The 5-year OS was 24% (95%CI: 21.6-26.0%) with a median OS of 1.7 years (95%CI: 1.6-1.8). Age ≥ 70 years at diagnosis, higher stage at diagnosis, and respiratory tract location were independent predictors for worse OS. Diagnosis in the period 2014-2019, MM located in the female genital tract, and treatment with immune or targeted therapy were independent predictors for better OS.

Conclusion: Since the introduction of immune and targeted therapies, OS has improved for patients with MM. However, the prognosis of MM patients is still lower compared to CM, and the median OS of patients treated with immune and targeted therapies remains fairly short. Further studies are needed to improve outcomes for patients with MM.