The current status of S-100B as a biomarker in melanoma

Melanoma is the most malignant type of all skin cancer types. It causes over 75% of all skin cancer related mortality. In the Netherlands, the total number of new diagnosed melanoma patients is expected to increase from 2400 patients in 2000 to 4800 patients in 2015. After surgical treatment, 20-28% of melanoma patients present with loco-regional recurrence, 26-60% with regional recurrences, and 15-50% with distant metastases. Early detection of lymph node (micro) metastases by means of a sentinel lymph node biopsy (SLNB) is therefore of crucial importance since early lymph node dissection decrease treatment morbidity and improve overall survival. However when patients present with palpable nodes, given the heterogeneity in survival, the suspicion rises that numerous patients have a form of subclinical dissemination, which can remain undetected by current modern imaging methods. Biomarkers could illuminate on this matter, although there is very little understanding of their biological significance. It can be expected that the strongest biological markers are surrogates of key biological events. The protein S-100B seems to be the best analyzed biomarker in melanoma. It has the potential to identify high-risk stage III melanoma patients who may benefit from adjuvant systematic treatment. In the stratification of new adjuvant therapeutic trials in patients with loco-regional recurrences, we therefore recommend the use of S-100B in the stratification. Since an effective (adjuvant) therapy for loco-regional metastatic and disseminated melanoma is recently introduced, the use of S-100B seems to alter dramatically in the near future.