Studying a complex tumor: potential and pitfalls.

Glioblastoma multiforme is a histopathologically heterogeneous disease with few treatment options. Therapy based on genomic alterations is rapidly gaining popularity because of the high response rate and high specificity. DNA copy number and exon-sequencing studies of glioblastoma multiforme samples have revealed recurrent genomic alterations in genes such as TP53, EGFR, and IDH1, but to date, this has not resulted in novel glioblastoma multiforme therapies. Identification of expression subtypes has resulted in new insights such as the association between genomic abnormalities and expression signatures. This review describes the types of genomic studies that have been performed and that are underway, the most prominent results, and the implications of genomic research for the development of clinical treatment modalities.