If I have read this abstract correctly, it looks like the results of the HERA trial have shown that FISH is much better than IHC at predicting who will benefit from herceptin.
Disease-free survival according to local immunohistochemistry for HER2 and central fluorescence in situ hydridization for patients treated with adjuvant chemotherapy with and without trastuzumab in the HERA (BIG 01-01) trial.
http://www.abstracts2view.com/sabcs/...07L_1069&terms=