Purpose: Immune complexes (IC) containing the tumor-associated antigen TA90 can be identified in the sera of melanoma patients. We have shown that an enzyme-linked immunosorbent assay for TA90-IC can detect subclinical metastasis before surgical treatment of early-stage melanoma. We assayed the TA90-IC levels of postoperative sera from patients with melanoma and evaluated their relationship to recurrence and survival.
Patients and methods: Multiple archival serum samples prospectively collected during postoperative surveillance of 166 patients with American Joint Committee on Cancer stage I, II, or III melanoma were analyzed for TA90-IC in a blinded fashion. Results were correlated with disease recurrence and survival determined by database and chart review.
Results: TA90-IC status in the early postoperative period was strongly correlated with survival. Five-year overall survival rates were 84% for TA90-IC-negative patients and 36% for TA90-IC-positive patients (P =.0001). Respective 5-year disease-free survival rates were 74% and 24% (P =.0001). The TA90-IC assay was a significant predictor of survival for both stage II and III patients. Multivariate analysis identified TA90-IC status as the strongest independent prognostic factor for both overall and disease-free survival. The TA90-IC assay was elevated in 54 (77%) of 78 patients who developed recurrent disease, becoming positive 19 +/- 7 months before clinical evidence of recurrence. Overall, the assay detected recurrence with a sensitivity of 78% and specificity of 77%. Exclusion of patients receiving postoperative immunotherapy with a polyvalent melanoma cell vaccine increased sensitivity and specificity to 92% and 86%, respectively.
Conclusion: The TA90-IC assay can accurately predict survival and detect the presence of subclinical disease after surgery for melanoma, which should be useful in selecting patients for adjuvant therapy. Because the TA90-IC assay detected recurrence on an average of 19 months sooner than did routine clinical and radiographic evaluation, it may allow more timely therapeutic interventions.