ABSTRACT
Companion and complementary diagnostic tests are performed using various methods, including IHC, in situ hybridization (ISH), real-time polymerase chain reaction, and next-generation sequencing. With the successes of molecular targeted drugs, such as trastuzumab, cetuximab, and imatinib, the importance of molecular pathologic diagnosis has been increasing. Immunohistochemistry is an experimental method for detecting the expression of specific proteins in tissue specimens that uses the antigen and its specific antibody binding reaction. In ISH is a molecular method used for the detection and localization of specific RNAs or DNAs in cells using tissue sections. Through this method, labeled RNA or DNA probes, which are complementary to a target gene sequence, are applied to tissue sections and hybridize with a target gene sequence in the cells. The hybrids can be detected by fluorescent ISH, silver ISH, or chromogenic ISH signal detection methods. A major advantage of ISH is that it is an in situ method that can provide histological findings.
