Prognostic factors and treatment outcomes in 444 patients with mucosal melanoma.

BACKGROUND: Mucosal melanoma (MM) is a rare but diverse cancer entity. Prognostic factors are not well established for Caucasians with MM.

PATIENTS AND METHODS: We analysed the disease course of 444 patients from 15 German skin cancer centres. Disease progression was determined with the cumulative incidence function. Survival times were estimated with the Kaplan-Meier method. Prognostic parameters were identified with multivariate Cox regression analysis.

RESULTS: Common anatomic sites of primary tumours were head and neck (MMHN, 37.2%), female genital tract (MMFG, 30.4%) and anorectal region (MMAN, 21.8%). MMAN patients showed the highest vertical tumour thickness (p = 0.001), had a more advanced nodal status (p = 0.014) and a higher percentage of metastatic disease (p = 0.001) at diagnosis. Mutations of NRAS (13.8%), KIT (8.6%) and BRAF (6.4%) were evenly distributed across all tumour site groups. Local relapses were observed in 32.4% and most commonly occurred in the MMHN group (p = 0.016). Male gender (p = 0.047), advanced tumour stage (p = 0.001), nodal disease (p = 0.001) and incomplete resection status (p = 0.001) were independent risk factors for disease progression. Overall survival (OS) was highest in the MMFG group (p = 0.030) and in patients without ulceration (p = 0.004). Multivariate risk factors for OS were M stage at diagnosis (p = 0.002) and incomplete resection of the primary tumour (p = 0.001).

CONCLUSION: In this large series of MM patients in a European population, anorectal MM was associated with the poorest prognosis.