Expression of p53, EGFR, pRb and bcl-2 proteins in pediatric glioblastoma multiforme: A study of 54 patients

Pediatric glioblastoma multiforme ( GBM) tumors, which have been established as 'de novo' neoplasms, are known to differ from their adult counterparts in terms of biology, genetics and ultimately survival of patients. In order to evaluate the utility of markers of tumor biology for refining prognostic assessment, we retrospectively analyzed 54 pediatric GBMs ( age range 9 months to 15 years) occurring at different anatomical sites in the brain, operated at our institute between 1995 and 2001. The expression of p53, epidermal growth factor receptor ( EGFR), bcl-2 and retinoblastoma proteins ( pRb) was analyzed by immunohistochemistry and the results were compared with the clinical profile, MIB-1 labeling index ( LI) and patient survival. p53 immunoreactivity was noted in 53.7% of cases, predominantly in thalamic ( 75%) and cerebral lobar ( 62.2%), followed by brainstem tumors ( 30%). It was absent in cerebellar tumors. p53-positive tumors had a higher MIB-1 LI, compared to p53-negative tumors ( p = 0.003). EGFR and bcl-2 overexpression was observed in 25.9% and 33.3% of cases, respectively, and loss of pRb expression was evident in only 7.4% of cases, indicating that loss of this gene function is not significantly involved in pediatric GBMs. p53 and bcl-2 expression were maximally noted in patients with poorer outcome. Our results indicate that p53 expression status is noted in a significant number of pediatric supratentorial neoplasms. p53 with bcl-2 overexpression is more often associated with ominous prognosis. Further molecular characterization would provide newer insights into the biology of these neoplasms and form a basis for future therapeutic decision making. Copyright (c) 2005 S. Karger AG, Basel.