Hey Rozebud,
Here's a few good places to start. All suggest that her2 tumors might be tamoxifen resistant, BUT that that adding herceptin (or iressa) might be effective.
Jeff
http://jncicancerspectrum.oupjournal.../895?view=full
http://jncicancerspectrum.oupjournal...?view=abstract
http://jncicancerspectrum.oupjournal...91-b?view=full