Several approaches that have been used previously for hematological malignancies have been applied to detect TMPRSS2:ERG exon fusion variants. These include fluorescent in situ hybridization (FISH) (2, 12, 14, 17, 23) , RT-PCR and sequencing (2, 7, 9, 13) , quantitative PCR (qPCR) (2, 8, 24) and array-based comparative genome hybridization (array CGH) (10) (11) (12) . FISH may be the most commonly used method, but it has relatively low resolution, and therefore, cannot accurately determine different fusion variants. Array CGH has a higher resolution but is costly and often fails when there is normal cell contamination.