Abundance of apoptotic neoplastic cells in diagnostic biopsy samples is not a prognostic factor in childhood primitive neuroectodermal tumors of the central nervous system

Purpose: To assess if the abundance of apoptotic tumor cells is an independ ent prognostic factor in primitive neuroectodermal tumors (PNET) of the cen tral nervous system. Patients and Methods: Formalin-fixed paraffin-embedded tumor tissue section s from 78 clinically well-characterized children with PNET were evaluated b y terminal deoxytransferase-mediated deoxyuridine-5'- triphosphate (dUTP) n ick-end labeling (TUNEL). Apoptotic indices (AI) were determined by countin g TUNEL-positive tumor cells either in the highest staining region (AI hot spot) or in at least 15 randomly chosen fields (AI random). The AI hot spot and AI random were then correlated with clinical variables and survival ou tcome. Results: AI hot spot (median 0.56%; range 0%-6.54%) and AI random (median 0 .30%; range 0%-3.21%) showed considerable intertumor variability. Moreover, 53% of the evaluated PNET showed a more than two-fold difference between A t hot spot and AI random, showing important intratumoral variability of the abundance of apoptotic cells in a subset of the evaluated PNET. No signifi cant associations were found between At hot spot and AI random with clinica l variables or survival outcome. Conclusion: The apoptotic index does not predict survival outcome and is no t specifically associated with clinical variables of prognostic significanc e in childhood PNET.