The potential of circulating cell-free RNA as a cancer biomarker: challenges and opportunities

INTRODUCTION: Cancer statistics show that recent improvements in cancer management are only mildly effective in the absence of reliable biomarkers for the detection, diagnosis and monitoring of malignant disease. Recently circulating nucleic acids have been suggested as potential biomarker candidates to fill this role. Areas covered: This review focuses on the different types of circulating RNA biomarkers under investigation, describing the latest advances in their development and application to clinical settings, as well as challenges that researchers face in the process. Immediate perspectives of the field are outlined, and authors' recommendations on the best progression path are provided. Expert commentary: The development of RNA-based cancer biomarkers is a thriving area of biomedical research that has progressed significantly over the last decade. However, it seems that it is now at the point, where unless several key issues are resolved, no significant progress can be made further. Currently several areas of biomarker research require re-assessment, as indicated by the latest findings regarding the biology of circulating nucleic acids and the accumulated data of their analysis using various techniques. Additionally, regulating agencies need to be working alongside researchers to facilitate faster and easier adoption of new effective biomarkers into the clinical practice.