The 2007 WHO classification of tumors of the central nervous system - what has changed?

As progress is being made in understanding the biology of cancer, revision to any current tumor classification is needed every 5 years or so. Technology of genomic analysis, among others, is evolving rapidly and new information has to be integrated to update any such classification. The fourth edition of the WHO classification of tumors of the central nervous system was published in 2007 and aims at establishing a nomenclature that is used and accepted worldwide, and at incorporating the latest advances in the field.

The 2007 WHO classification is focused on neoplasms of the central nervous system. Several newly recognized entities, which have become established since the previous, 2000 classification have been included. A wealth of genomic data has been added and distinct genetic alterations represent criteria to define tumor subsets, such 1p/19q codeletion in oligodendrogliomas. Yet, morphology is still the gold standard of the WHO classification.

Other novel clinically relevant and carefully defined entities are expected to join the growing list of brain tumors in the near future. New tools in cytogenetics and molecular genetics are rapidly changing the field of central nervous system neoplasms. Integrating genetic data in clinical routine practice is essential. A true histogenetic nomenclature may be the next step for the WHO classification of central nervous system neoplasms.