Epidermal growth factor receptor gene amplification as a prognostic markerin glioblastoma multiforme: Results of a meta-analysis

Amplification of the epidermal growth factor receptor (EGFR) gene occurs in approximately 40% of cases of glioblastoma multiforme (GBM) and is conside red a possible marker of poor prognosis. This report presents the results o f a metaanalysis of the available data addressing this issue. Using a prosp ective protocol, a meta-analysis was designed to assess the possible progno stic importance of EGFR gene amplification in GBM. One-year survival data d erived from seven published studies were analyzed using a general variance based method employing confidence intervals described by Greenland. The out come of interest was a summary relative risk (RR,) reflecting the risk of d eath at 1 year from diagnosis associated with EGFR amplification-positive v ersus -negative disease. Prior to calculation of a RRs, an analysis for hom ogeneity (Q) showed Q to equal 9.21. With 6 df, this yielded a P value of 0 .12, indicating that the data were homogenous and could be combined in a me ta-analysis. Pooling all available studies gave a RR, of 1.13 with a 95% co nfidence interval of 0.71-1.80, a nonstatistically significant result. The data suggest that the available studies are insufficient for determining wh ether EGFR gene amplification is of prognostic value in GBM. Important pote ntial confounding factors are the influence of underlying EFGR gene mutatio n on patient survival and lack of control for important known clinical prog nostic indicators in many studies. Future work must incorporate these param eters in multivariate analyses to determine whether EGFR gene alterations a re truly associated with poor clinical outcome.