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Serum S100B levels correlate with stage, N status, mitotic rate and disease outcome in melanoma patients independent to LDH.

PURPOSE
S100B protein is currently used as an immunohistochemistry marker to confirm melanoma diagnosis in biopsy specimens. Moreover, accumulating evidence supports its potential use as a tumor biomarker in blood. This study aimed to explore the potential uses of serum S100B protein as a biomarker in melanoma patients.


METHODS
From 2012 to 2015, 107 sequential patients were diagnosed and treated for melanoma. All patients were tested for serum S100B and lactate dehydrogenase (LDH) at diagnosis and during their regular follow-up. Potential correlations between S100B serum levels and baseline characteristics and its impact on survival were assessed.


RESULTS
S100B serum levels were within normal limits in patients with stages I and II, elevated in stage III, and very high in stage IV. In bivariate analysis, serum S100B levels >0.11μg/l and stage IV were the only independent prognostic factors associated with poor survival. Furthermore, S100B >0.5μg/l was associated with stage IV and poor survival. However, there was no significant association with LDH. S100B serum levels were positively correlated with mitotic rate (p=0.003), but only in stage IV patients (p=0.015). In stage III, a statistically significant difference in S100B serum levels were observed between N3, N2 and N1 stages, with higher levels for N2 (p=0.012) and N3 (p=0.009) compared to N1, and no difference between stages N2 and N3 (p=1.000). Also, no correlation was found between the number of primary melanoma lesions and S100B.


CONCLUSIONS
S100B serum levels reflect tumor load, correlate with response to treatment, might identify patients who are at increased risk of disease relapse, may predict prognosis independent to LDH, and could be used as early biomarkers of tumor recurrence.