| Abstract: | Neuroendocrine tumors (NET) belong to the group of rare tumors, though their incidence is increasing. Diagnosis and treatment vary among groups of different primary origins. NETs of gastrointestinal origin (GEP-NET) are slow growing tumors; however, most patients with GEP-NET are not diagnosed until the metastatic spread of the disease has already occurred. Somatostatin analogues are the mainstream treatments of symptom and tumor growth control in these patients. Other systemic therapies depend on the biologic potential of the tumor. S100B – Tumor marker in cutaneous melanoma Barbara Perić, Ivana Žagar, Srdjan Novaković, Janez Žgajnar and Marko Hočevar Introduction. An increased level of serum S100B can serve as a marker of metastatic spread in patients with cutaneous melanoma (CM). In patients with elevated S100 B and/or clinical signs of disease progression, a PET-CT scan is a valuable tool for discovering metastases and planning treatment. The aims of this study were to determine whether regular measurements of serum S100B are a useful tool for identifying patients with CM metastases and for evaluating the diagnostic value of PET-CT during the follow-up. Methods. From September 2007 to February 2010, 115 CM patients included in regular follow up at the Institute of Oncology Ljubljana were appointed to receive PET-CT scans. They included 82 (71.3%) patients with clinical signs of disease progression and 33 (28.7%) asymptomatic patients with two subsequent elevated values of S100B. Sensitivity, specificity, positive and negative predictive values (PPV, NPV) of S100B and PET-CT were calculated using standard procedures. Results. Disease progression was confirmed in 81.7% of the patients (in 86.5% of patients with clinical signs of disease progression and in 69.7% of asymptomatic patients with elevated S100B). Sensitivity, specificity, PPV and NPV of S100B was 33.8%, 90.9%, 96.0% and 17.5%, respectively, in patients with clinical signs of disease progression. For 20.0% of the patients increased serum S100B was the only sign of disease progression. Sensitivity and PPV of S100 in this group of patients were 100.0% and 69.7%, respectively. PET-CT disease progression was diagnosed in 84.2% of symptomatic patients and in 72.7% of asymptomatic patients with elevated S100B. The sensitivity, specificity, PPV and NPV of PET-CT for symptomatic patients was 98.5%, 90.9%, 98.5% and 90.9%, respectively, and 100%, 90.0%, 95.8% and 100%, respectively, for asymptomatic patients with elevated S100. Conclusions. Measurements of serum S100B during regular follow-up of patients with CM are a useful tool for discovering disease progression in asymptomatic patients. The value of its use increases if measurements are followed by extended whole body PET-CT. |
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