Serum TA90 immune complex assay can predict outcome after resection of thick (≥4 mm) primary melanoma and sentinel lymphadenectomy

Background: We hypothesized that the postoperative serum level of TA90-IC, an immune complex of a 90-kDa tumor-associated antigen and its antibody, might have a significant correlation with recurrence and survival in patients with thick primary melanomas. Methods: We used our prospective melanoma database to identify all patients who underwent wide local excision and sentinel lymphadenectomy for primary melanomas greater than or equal to4 mm and from whom sera had been collected and cryopreserved within 6 months after surgery. These sera were analyzed in a blinded fashion for TA90-IC status by using our double-determinant enzyme-linked immunosorbent assay. Results were correlated with disease-free survival (DFS) and overall survival (OS). Standard prognostic factors for melanoma were then compared with TA90-IC status for the prediction of DFS and OS. Results: The sensitivity and specificity of the TA90-IC assay for predicting recurrence were 70% and 85%, respectively. Five-year DFS and OS rates were higher for the TA90-IC-negative group than the positive group. The differences in DFS and OS between the TA90-IC-negative and -positive groups, were significant. At a median follow-up of 25 months, multivariate analysis identified postoperative TA90-IC status and sex as significant predictors of DFS. TA90-IC status was the only independent prognostic factor with multivariate analysis. Conclusions: TA90-IC status after resection of thick primary melanoma accurately predicts outcome. A positive postoperative TA90-IC level might affect a decision regarding adjuvant therapy, regardless of regional nodal status.