Telomere Length in Renal Cell Carcinoma: The Jekyll and Hyde Biomarker of Ageing of the Kidney.

Renal cell carcinoma (RCC) is a heterogeneous group of cancers where the clear cell (ccRCC) is the most common and the most lethal. The absence of accurate diagnostic and follow-up biomarkers along with the time-limited response to therapies may explain the lethality and shows the necessity of new sensitive and specific biomarkers. One of the most studied molecules are the telomeres: specialized ribonucleoprotein structures that keep the structural integrity of the genome. Among other features, telomere length (TL) has been widely studied in several tumor models regarding its biomarker potential, due to the easy detection and quantification. The scope of this review was to analyze all the information about this parameter in RCC. There was some disparity in the results of the studies, since some pointed to an association between short TL and risk or poor outcome of RCC; others between long TL and RCC outcome and some did not find any association. We propose some epidemiological and biological explanations to these differences. The telomeres may play a dual role during RCC carcinogenesis in the early stages, short telomeres may increase RCC risk and in late carcinogenesis, long telomeres seem to be associated with tumor prognosis. However, the controversy of the results along with the lack of specificity are some problems that need to be clarified for the usage of TL as a prognostic biomarker.