Impact of lymph node metastases on serum level of melanoma inhibitory activity in stage III melanoma patients.

Melanoma patients in stage III have a considerable recurrence rate. The 10-year survival in this stage depends on the number and size of affected nodes. Currently, there is no optimal serum marker for early detection of relapse available. The goal of the study was to assess the utility of melanoma inhibitory activity (MIA) serum marker in the follow up and primary diagnosis of stage III melanoma patients. One hundred and thirty-eight melanoma patients in stage III at time of primary diagnosis were analyzed at time of primary diagnosis and during periodical routine follow up both for serum MIA using an enzyme-linked immunosorbent assay and for serum lactate dehydrogenase (LDH). Results were correlated with the positivity of the sentinel lymph node (SLN) and the number of lymph node metastases in the completion lymph node dissection at time of primary diagnosis. During follow up, the overall survival time was assessed using the Kaplan-Meier method in terms of elevated MIA (>12 ng/mL) values. Regarding SLN status, significant differences of MIA values (P = 0.024) and LDH (P = 0.007) were found, both within the normal cut-off. Having lymph node metastases in the completion lymph node dissection, significantly higher MIA values (12.55 ng/mL [±0.48], P < 0.0001) were found. In patients with three or more tumor-positive nodes, MIA values were significantly higher when compared to patients with one or two affected nodes (P = 0.024). In the routine follow-up, stage III patients with an MIA value of more than 12 ng/mL had a five times higher risk for developing recurrences (P < 0.0001). Patients with relapsing disease had a significantly (P < 0.0001) higher mean MIA value (13.76 ng/mL) compared to patients without relapse (7.52 ng/mL). The MIA serum marker can be helpful in patients undergoing lymph node dissection. Furthermore, during follow up, patients showing relapsing diseases can have an elevated MIA value.