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

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.

The aim of this study was to analyze the clinical and laboratory characteristics of 28 cases of primary mucosal melanoma in Southwest China.

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).

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.