Serum TA90 immune complex assay can predict outcome after resection of thick (> or =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 > or =4 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.