[Genetic alterations in neuroblastoma and their usefulness for clinical management]

Neuroblastoma, the most frequent solid extracranial tumor of childhood, is characterized by a wide variability of its clinical course. The most important clinical prognostic markers are stage and age at diagnosis, but these markers are insufficient to predict outcome reliably and to determine treatment intensity. Recent evidence indicates that neuroblastoma can be considered as a "genetic disease", firstly by the recent observation that certain alleles of specific genes significantly increase the relative risk to develop neuroblastoma, and the discovery of mutations in genes such as ALK or PHOX2B in rare familial cases. On the other hand, a large number of recurrent genetic somatic alterations have been described in neuroblastoma. Recent technological advances, such as array-CGH (comparative genomic hybridisation), now enable the analysis of these markers in a single step and allow the definition of genomic profiles associated with typical clinical features. Numerical chromosome alterations are observed more frequently in tumors of younger children with localised disease and a good prognosis, whereas segmental chromosome alterations are found more frequently in tumors of older children with advanced stages of disease and a poorer outcome. Future therapeutic stratification schemes can make use of the tumor genomic profile by proposing less intense treatment for infants with a neuroblastoma harboring a favorable tumor genomic profile, while intensifying treatment in case of a defavorable tumor genomic profile. Such approaches require standardisation of the molecular techniques and the interpretation of results for application in international trials.