Kovarikova H, et al. - During this trial, miR-21 underwent a comprehensive analysis in order to determine its role as a prognostic biomarker in sinonasal squamous cell carcinoma. The results disclosed the involvement of miR-21 upregulation in the tumorigenesis of sinonasal carcinoma. It was related to a poor prognosis. Hence, it was deduced that miR-21 could serve as a valuable prognostic biomarker.