High microvessel density in primitive neuroectodermal brain tumors of childhood.

Microvessel density (MVD), a measure of tumor angiogenesis, has been shown to correlate significantly with overall and progression-free survival outcomes in various cancers including astrocytic brain tumors. To assess if the MVD is an independent prognostic factor in primitive neuroectodermal tumors (PNET) of the central nervous system, formalin-fixed paraffin-embedded tumor sections of 78 children with PNET were studied by CD34 immunohistochemistry to highlight endothelial cells. Microvessel density was determined in the most active area of neovascularization according to well-established methods. While it was shown that MVD showed considerable inter-tumor variability (median 75; range 20-345 microvessels per 0.7 mm2 field), no significant associations were found between MVD and metastasis or survival outcomes. We conclude that many PNETs are highly vascular CNS tumors, indicating potent angiogenic activity. Therefore, these tumors would be good candidates for antiangiogenic strategies. However, MVD determined in the most active area of neovascularization is not a predictor of metastatic potential or survival outcomes in childhood PNET.