In the follow-up of melanoma patients, there is still a need for an optimal serum marker to discover recurrent disease at an early stage. Melanoma inhibitory activity (MIA) has been investigated as a serum marker for cutaneous melanomas. Although the prognosis for melanoma based on stage is generally good, the disease identified at later stages is associated with high levels of morbidity and mortality. The value of MIA testing in early-stage melanoma was the goal of this study. Five thousand three hundred and thirty-four MIA serum values from 1079 consecutive melanoma patients in stages I and II were obtained during routine follow-up at scheduled intervals. Sensitivity and specificity of MIA were calculated. The area under the receiver-operating characteristics curve and Somers' Dxy rank correlation were assessed. Metastasis occurred in 137 patients with a sensitivity of MIA testing of 67.6% in stage I and 65.6% in stage II patients. The specificity was 76.9% for stage I and 66.7% for stage II patients. The most reliable normal upper limit for MIA was redefined at 12.0 ng/ml, when compared with 8.8 and 15.0 ng/ml. Multivariate analysis revealed significantly more frequent false-positive values in elderly women and in men with an increased Breslow thickness.MIA adapted with a new cut-off level is then a useful serum marker even in the follow-up of not yet relapsed early-stage melanoma patients. In older women and in men with an increased tumor thickness, the higher rate of false-positive values should be considered before starting further diagnostics. Additional prospective studies to clarify the clinical combination with other serum markers seem promising.

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.