Prognostic Implications of Protein S-100β Serum Levels in the Clinical Outcome of High-Risk Melanoma Patients

Objective: It was the aim of this study to analyze the clinical value of the determination of serum S-100β protein in high-risk melanoma patients. Patients and Methods: Patients were tested for serum S-100β protein by luminoimmunometric assay after melanoma surgical excision, before starting interferon-α 2b and every 3 months thereafter, until treatment was completed. Results: Ninety-seven patients were included in the study. Median follow-up was 62.9 months (range 32.7–87.4). High baseline S-100β levels were associated with positive lymph node status (p = 0.02). High S-100β levels (during therapy) showed a relation with positive lymph node status (p = 0.014), number of positive lymph nodes (p = 0.01), macroscopic lymph node involvement (p = 0.002) and second melanoma diagnosis at study entry (p = 0.001). By univariate analysis, high baseline S-100β levels were associated with disease-free survival (p = 0.004) and overall survival (p = 0.0007). Similarly, high S-100β levels during therapy were associated with disease-free survival (p < 0.0001) and overall survival (p < 0.0001). In the multivariate analysis, high S-100β levels during therapy (hazard ratio 1.017, 95% CI 1.008–1.026; p < 0.0001) and high baseline S-100β levels (hazard ratio 3.31, 95% CI 1.10–9.89; p = 0.032) were independent prognostic factors for overall survival when compared with low levels while on therapy and low baseline S-100β levels, respectively. Conclusions: These results provide evidence of the clinical usefulness of serum S-100β level determination in high-risk melanoma patients. S-100β serum determination should be considered to be included in clinical trials that test adjuvant therapies in melanoma patients.