Background: The aim of this study was to investigate the feasibility of using serum miR-221 as a noninvasive prognostic biomarker for cutaneous malignant melanoma (CMM).
Material and Methods: We measured the expression levels of miR-221 in serum samples from 72 CMM patients and 54 healthy controls by real-time quantitative polymerase chain reaction (RT-PCR). The overall survival (OS) and disease-free survival (DFS) were calculated using the Kaplan-Meier method. The differences between the survival curves were tested by using the log-rank test. The COX proportional hazards regression model was used to determine the joint effects of several variables on survival.
Results: The serum miR-221 levels were significantly higher in patients with CMM than in healthy controls (p<0.0001). Patients with high serum miR-221 levels had a significantly lower 5-year OS rate (22.1% vs. 54.6%; P=0.018) and RFS rate (12.5% vs. 45.2%; P=0.008) than those with low serum miR-221 level. In a multivariate Cox model, we found that miR-221 expression was an independent predictor of poor 5-year OS (hazards ratio [HR]=3.189, 95% confidence interval [CI]=1.782–6.777, P=0.007) and 5-year DFS (HR=2.119, CI=1.962–8.552, P=0.01) in CMM patients.
Conclusions: Our data indicate that serum miR-221expression level has prognostic value in patients with CMM.

Keywords: Case-Control Studies, Female, Gene Expression Regulation, Neoplastic, Humans, Male, Melanoma - pathology, MicroRNAs - metabolism, Middle Aged, Prognosis, Survival Analysis