Know HER2 status w/out test?

Hi all-
A friend of mine was recently Dx'd with BC and her onc told her she did not need a FISH. She said he was "very confident" that she was HER2 negative because of her ER/PR + and who knows what else...

She had the IHC (I think thats the acronym) and perhaps he is basing his conclusion off that. I had that test too and results were barely positive. Only after I had the FISH test did I find out just how aggressive it was.

I wonder if his advice is good... She really likes him and trusts him... and I am not sure if his telling her she does need FISH is good advice!

Maria