[al from Canada]

John,
There is very limited research on this subject but if we put together the bit of literature:

1. Herceptin prevents re-occurrance in about 56% of patients. This leads me to believe that there are cancer cells out there waiting to be destroyed

2. We know that cancer cells can morph into both HER2+ and ER+ from their negative counter parts.

3. We know that one's own immune system will also kills cancer cells.

Conclusion (my opinion): There may be a remote possibility that there are a few ER+ cancer cells circulating in your wifes system, waiting to be activated. That said, I don't know if I would chance it however, if you investigate DIM and I3C, which are supplements which modify estrogen metabolism, i certainly wouldn't take one without the other. ie, HRT without DIM or I3C.

I think you are treading on thin ice.

Good luck,
Al