Sensitivity, specificity, positive and negative predictive value of serum S-100 beta protein in patients with malignant melanoma

Abstract

Purpose: To establish the sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of serum S-100 beta protein (sSB) in patients with malignant melanoma (MM), based on its concentration in the peripheral blood and the likelihood ratio (LR) for the whole group of patients with MM, as well as for each separate clinical stage. Patients and methods: sSB was determined immunoluminometrically in 172 patients with histologically confirmed MM. Sera from 64 healthy subjects were used as controls. Results: Increased values of sSB were detected in 65 out of 172 patients with MM, and in 5 cases among healthy subjects. Sensitivity, specificity, PPV and NPV were 38%, 92%, 93% and 35%, respectively. In stage I 1/29 patients had increased values of sSB, in stage II 3/34, in stage III 13/47 and in stage IV 48/62 patients. Sensitivity, specificity, PPV and NPV for stage I were 3%, 92%, 17% and 68%, respectively; for stage II 9%, 92%, 37% and 65%, respectively; for stage III 28%, 92%, 72% and 63%, respectively; and for stage IV 77%, 92%, 91%, and 81%, respectively. The LR for sSB values of >13 μg/l was 5 for the whole group of patients with MM, 0.4 for stage I, 1 for stage II, 3 for stage III and 10 for stage IV. Conclusion: Based on our results we conclude that sSB is a reliable serum marker for the diagnosis of stage IV MM.