Current outcome predictors in childhood primitive neuroectodermal tumors

Central nervous system primitive neuroectodermal tumors (PNET) including cerebellar PNET (medulloblastoma, PNET/ MB) are the most common malignant brain tumors in childhood. Because of the high risk of leptomeningeal dissemination, standard postoperative treatment for PNET includes craniospinal radiotherapy and chemotherapy. Such treatment causes long-term morbidity including endocrine and growth disturbances, as well as neurocognitive dysfunction, which is particularly severe in young children. Over the last years, neurotrophin receptor TrkC, neuregulin receptor ErbB2 and oncogene MYC have been identified as biological prognostic factors in PNET/MB. High TrkC mRNA expression, low ErbB2 protein expression and low MYC mRNA expression are powerful independent predictors of favorable clinical outcome in PNET/MB. Upon validation in ongoing prospective biological studies, these biological factors may define risk groups and help direct therapy decisions for children with PNET/MB. In PNET with favorable biological factors and no evidence of leptomeningeal tumor dissemination, therapy with reduced craniospinal radiation might retain the efficacy but reduce the toxicity and therefore improve the quality of life for the survivors. (J Pediatr Neurol 2003; 1(2): 75-82).