MYC messenger RNA expression predicts survival outcome in childhood primitive neuroectodermal tumor/medulloblastoma

Purpose and Experimental Design: Cerebellar primitive neuroectodermal tumor s/medulloblastomas (PNET/MB) are the most common malignant brain tumors in childhood. To identify PNET/MB biological prognostic factors that define a patient group with a sufficiently good prognosis to permit a reduction in t reatment intensity, we determined the expression levels of MYC mRNA in fres h frozen tumor samples from 26 PNET/MB patients using semiquantitative reve rse transcription-PCR. Results: MYC mRNA expression levels in primary PNET/MB showed a wide range with a 22-fold difference between the highest and lowest values and did not correlate with MYC gene amplification. MYC mRNA expression was an independ ent significant prognostic factor for progression-free survival outcome and was more predictive than standard clinical factors. The combination of low MYC mRNA expression and high TrkC mRNA expression identified a good outcom e group of PNET/MB patients (n = 7) with 100% progression-free survival aft er a median follow-up time of 55 months (range, 15-91 months). Three of the se seven good outcome patients survived without radiotherapy. Conclusions: Low MYC mRNA expression is a powerful independent predictor of favorable clinical outcome in PNET/MB. Assessment of MYC mRNA levels is fe asible and may be incorporated in prospective PNET/MB clinical trials to ai d in treatment planning for patients with PNET/MB on confirmation of our re sults in larger studies.