As the test of choice for
chromosomal rearrangements, FISH was successfully
applied to frozen as well as formalin-fixed paraffinembedded (FFPE) prostate cancer samples with high
sensitivity and specificity. Initially, a kit containing
dual-color ERG break-apart probes that can identify
rearrangement of the ERG gene but do not indicate the
5’-partner to which ERG is fused to, was used [48,49].
Later on, a tricolor FISH assay was developed by combining the red/green break-apart probes for TMPRSS2
with an orange-labeled fusion probe for the 3’ region of
ERG [50,51]. Recently, a four-color FISH assay was
reported, which allows the detection of either TMPRSS2
or ERG rearrangements regardless of the partner gene