Evaluation of a microRNA-based Risk Classifier Predicting Cancer-Specific Survival in Renal Cell Carcinoma with Tumor Thrombus of the Inferior Vena Cava

(1) BackgroundClear cell renal cell carcinoma extending into the inferior vena cava (ccRCCIVC) represents a clinical high-risk setting. However, there is substantial heterogeneity within this patient subgroup regarding survival outcomes. Previously, members of our group developed a microRNA(miR)-based risk classifier - containing miR-21, miR-126 and miR-221 expression - which significantly predicted cancer-specific survival (CSS) of ccRCCIVC patients. (2) MethodsExamining a single-center cohort of tumor tissue from n = 56 patients with ccRCCIVC, we measured expression levels of miR-21, miR-126 and miR-221 by qRT-PCR. Prognostic impact of clinicopathological parameters and miR expression were investigated via univariate and multivariate cox regression. Referring to the previously established risk classifier, we performed Kaplan Meier analyses for single miR expression levels and the combined risk classifier. Cut-off values and weights within the risk classifier were taken from the previous study. (3) ResultsmiR-21 and miR-126 expression were significantly associated with lymphonodal status at time of surgery, development of metastasis during follow-up, and cancer-related death. In Kaplan Meier analyses, miR-21 and miR-126 significantly impacted CSS in our cohort. Moreover, applying the miR-based risk classifier significantly stratified ccRCCIVC according to CSS. (4) ConclusionsIn our retrospective analysis, we successfully validated the miR-based risk classifier within an independent ccRCCIVC cohort.