[Histonet] Re: HER-2

[Bob Richmond]

Mark Tarango notes:

>>Many pathologists, if they have any doubt about the score will just say that it is 2+ so that its gets HER2 by FISH which is considered the best method for determining HER2 status.<<

On one busy pathology service I worked in 2004-2006 we were quite
explicit about overcalling HER-2 by IHC 2+. If we had any doubts at
all, we sent out the FISH. The cost is trivial compared to the cost of
treating a woman with trastuzumab (Herceptin).

It's important to understand that IHC and FISH do not measure the same
thing - IHC is looking at the excessive amount of the gene product,
while FISH is looking at amplification of the gene itself. Neither is
necessarily the "best method". Some oncologists want both methods done
on all cases.

PCR further complicates the situation. I think some reference labs now
consider this the preferred HER-2 method for adenocarcinomas of the
stomach and esophagus.

Bob Richmond
Samurai Pathologist
Maryville TN