A Brief History, the Progress in the Variants of Therapies against Metastatic Neoplasms, and the Role of Pathologists.

Chemotherapy originated in the early 1960s. The initial chemotherapeutic agents focused on blocking metabolic pathways and found substantial success in certain types of tumors, but they are generally considered toxic to all normal and tumor cells, and they have significant side effects. As more scientific studies began to identify many new, specific targets and mutations, along with a multitude of growth pathways in tumor cells, new agents targeting cell growth pathways began to emerge in the late 1990s and early 2000s. In 2003, a method called morphoproteomics was developed to evaluate the immunohistochemical protein expressions of target markers in tumors, and it has been considered a pioneering method for guiding targeted therapy. Subsequently, many genomic techniques have been established for identifying specific mutations and tumor markers in order to guide the targeted therapy. More recently, immuno-oncology therapy targeting specific immune markers has been rapidly developed, and the immunohistochemical evaluation of specific immune markers such as PD-L1 demonstrates further expansion of oncologic morphoproteomics. This brief review will focus on the role of pathologists in developing various techniques and guiding targeted therapies during the era of personalized medicine.