Tissue Handling and Specimen Preparation in Surgical Pathology: Issues Concerning the Recovery of Nucleic Acids from Formalin-Fixed, Paraffin-Embedded Tissue (Review Article)
Nucleic acid–based diagnostics are of great utility in molecular medicine but have been slower to reach the clinic than had been anticipated. The success of these platforms as biomarkers of disease is dependent on their reduction to an assay that is reproducible and widely applicable. (1,2) One hurdle in the introduction of nucleic acid-based diagnostics is the nature of the specimen from which the nucleic acids are obtained. Most hospitals and clinics lack the infrastructure to store and archive frozen tissue for isolation of RNA and DNA. (3) For tissue-based nucleic acid assays to enter the clinical setting, nucleic acids must be obtainable through the current practices of diagnostic histopathology. The current practice of specimen preparation is diverse and lacks strict standardization or well-defined standard operating procedures. As a result, significant diversity is found in the quality of the analyte source, namely, formalin-fixed, paraffin-embedded (FFPE) tissue. This report summarizes the challenges the field faces and provides guidance on how to accomplish the goal of standardization. By providing this information to investigators in the clinic, pathology laboratory, and research environments, the collection of tissue in clinical trials, as well as in routine medical care, can be improved. The goal is to elevate the quality of FFPE tissue obtained in clinical trials as the basis for the discovery and validation of new biomarkers. Central to these efforts is the appreciation that tissue is no longer used only for microscopic interpretation of histopathology, but also for molecular assays of both nucleic acids and proteins. With the introduction of molecular assays, tissue becomes an analyte, whose specification of quality is an element of the validated assays performed with it.