Gene Mutation and S100 Protein can be Prognostic Predictive Factors for Mucosal Melanoma Patients

BACKGROUND: Primary mucosal melanoma is a rare tumor that is usually diagnosed at advanced stages. It is of unknown etiopathogenesis with poor prognosis due to unfavorable response to treatments. METHODS: The aim of this study was to analyze the clinical and laboratory characteristics of 28 cases of primary mucosal melanoma in Southwest China. RESULTS: The mean age of the patients was 57 years, and 12 patients (43%) were men. Gene mutations were detected in 25% of the study population, and patients with gene mutations had a lower risk of relapse compared to patients without mutation (HR 0.258, p = 0.048). The study population had mucosal melanoma originating from head/neck (46%), anorectum (43%), and genital tract (11%). Patients with mucosal melanoma originating from genital tract had a higher peripheral blood lymphocyte-to-monocyte ratio (6.7) and a larger number of eosinophil (0.34 x 109/L) when compared to patients with mucosal melanoma originating from head/neck (3.1; 0.16 x 109/L) or patients with mucosal melanoma originating from anorectum (4.3; 0.14 x 109/L). At diagnosis, 3 patients (11%) developed organ metastasis. Patients with organ metastasis had a higher level of S100 protein (0.706 ng/mL) when compared to patients without metastasis (0.095 ng/mL) or patients with lymph node metastasis (0.067 ng/mL). S100 protein could be used to predict organ metastasis (cutoff value, 0.0935 ng/mL; AUC, 0.924; sensitivity, 0.89; specificity, 0.90). CONCLUSIONS: Among primary mucosal melanoma patients, gene mutations are associated with longer disease-control survival. S100 protein could help to improve the stratification process with a high risk of tumor progression.