An Update on Immunohistochemistry in Translational Cancer Research

Immunohistochemistry (IHC) takes advantage of the specific binding between antigen and antibody to measure the presence and abundance of antigen while simultaneously providing morphologic context on a tissue section. Since the revolutionary application of heat-induced epitope retrieval methods on formalin-fixed paraffin-embedded tissues, which started in early 1990s, IHC has been routinely used in diagnostic pathology. This approach has also enabled mining of the rich archives of pathologic specimens for exploration in translational cancer research. Newer IHC biomarkers are being continuously found as aids in differential diagnosis, prediction of outcome or response to molecular-targeted therapies. These are prime examples for translational cancer research. The last decade has witnessed some significant improvements in the use of this technology. This review provides an overview on the current status of IHC as applied in translational cancer research, commenting on the underlying principles in specimen preparation, reagent choice, staining procedure, and results evaluation so that both beginners and seasoned users could appreciate the key factors and benefit from this update