KNL-1 Pathologic diagnosis of brain tumors in the molecular era

Abstract

The WHO Classification of CNS Tumors, first published in 1979, was revised four times during the recent four decades. The revision was based on the refinement of tumor entities and introduction of new entities, which were facilitated by the development of new investigative techniques, such as immunohistochemistry and molecular cytogenetics. More sophisticated approaches including NGS and methylation analysis will introduce more molecularly defined entities in the next WHO Classification. The molecular analyses are a very powerful tool for brain tumor research. They have disclosed molecular mechanisms of several tumors and discovered unrecognized tumor entities till then. More precise biologic behavior could be estimated by molecular profiles. Furthermore, the development of novel molecular-targeted therapies will be expected. In the clinical practice, brain tumors should be diagnosed stepwise. First, clinical and image information is mandatory. Histopathologic and immunohistochemical findings should be evaluated within the clinical context. For molecularly defined tumors, genetic analyses are necessary. Following the stepwise procedures, the risk of falling in pit-falls may be decreased. In the molecular era, the integrated diagnosis, combined histopathologic and molecular information, of brain tumors is necessary. Recently, the Japanese Society of Pathology (JSP) has started the project which foster next-generation pathologists interested in rare cancers including brain tumors. In addition, some molecular information could be gained through the consultation system run by JSP and the National Cancer Center Japan. To adapt the next, more detailed molecular classification, it may be necessary that the cancer genome panel test become available within the national health insurance system.