Serum S-100B protein is a strong independent prognostic marker for distant-metastasis free survival (DMFS) in stage III melanoma patients: An evaluation of the EORTC randomized trial 18952 comparing IFNα versus observation

8518 Background: S100B serum levels have been reported to correlate with tumor stage and outcome, especially in metastatic melanoma. In the EORTC 18952 randomized trial assessing the value of intermediate doses (10 MU or 5 MU) of IFNa vs Observation, a side study on S100B has been set-up in order to assess 1) the prognostic importance of initial measurement of S100B; 2) the risk of developing distant metastases in patients with a S100B≥0.2 μg/l; 3) the prognostic importance of the latest measurement of S100B level on the subsequent outcome. Methods: The serial measurements of S100B, made by immunoluminometric assay LIA-mat (Sangtec Medical, Sweden) have been performed at randomization in 18952 study, at end of 4-week IFNa induction/observation, and thereafter, at month 1, 3, 6, 9, 12, 16, 20, 24, 30 and 36. The prognostic impact regarding DMFS of the latest value of S100B was assessed via the Cox time-dependent model. Results: A total of 211 patients, stage IIb (N=51) or stage III (N=160), were randomized...