Evaluation of S-100beta assays for the prediction of recurrence and prognosis in patients with AJCC stage I-III melanoma.

We performed prospective serial studies on 266 melanoma patients undergoing surgery for high risk primary or lymph node metastases to assess the predictive value for recurrence of melanoma of S-100beta detection in the serum using immunoradiometric assay (IRMA) or Immunoluminometric assay (LIA-mat). The tests for S-100beta were most frequently positive in the first 3 months after surgery. Results of the assays did not show a strong correlation with clinical stage of the disease. Studies on a cohort of 147 patients who had been followed for a minimum of 2 years post-surgery were carried out to assess the sensitivity of the assays for identifying patients who develop recurrence of their melanoma. The LIA-mat and IRMA assays detected S-100beta in the serum of 47.5% and 23%, respectively, of the subset of 61 patients who developed recurrence of disease. By Kaplan Meler analysis, patients positive for S-100beta by LIA-mat assay in the first 3 months post-surgery were shown to have an approximately 2.7 times shorter disease-free survival (DFS) period than patients negative for S-100beta. This was significant by log rank analysis. Multivariate analysis indicated that the presence of S-100beta was an independent prognostic determinant of DFS, and was independent of tumour thickness and lymph node status. This prospective analysis in a large number of patients suggests that assays for S-100beta in patients following surgical resection of AJCC stage I-III melanoma are of limited value for identifying patients who will develop recurrence of their disease. The results of the LIA-mat assays, but not the IRMA assays, do however provide an additional measure of prognosis that is independent of existing measures.