Validation by microarray data evaluation: miR-21 and 21FK score stratify OS risk in an independent validation cohort. Kaplan-Meier survival curves have been reported. miR-21 expression levels were measured by microarray, and cutoffs were based on the median expression levels. (A) Patients with high miR-21 expression had a significantly poorer prognosis in terms of OS. (B) Patients with a high 21FK score (2/2 and 1/2) showed a significantly poorer prognosis in terms of OS than for patients with a low 21FK score (0/2). Statistical differences between curves were calculated with the use of the log-rank test. In the main text the P values were reported according to Cox regression analyses associated to hazard ratio computation.