[Lani]

NancyL--have any other members of your family had( her2+) breast cancer?

I know they have only been testing for her2 rather recently making it difficult to know if those with breast cancer 10 or more years ago were her2+

There is a paper describing an X-linked her2+ breast cancer (usually ER+) having to do with a gene called Fox P3, which is found on T regulatory cells (part of the immune system)

Perhaps her2 testing was not that good when your sister had her primary--even now it is imperfect.

I met some nurses who work at Genentech at a breast cancer conference (they were there to get their continuing medical education credits) several years ago who said they had some mother-daughter pairs who had both been treated with herceptin.

If there is such a thing (hereditary her2+ breast cancer) it is probably rare, but if you don't go looking for it ie, retesting tumor specimens of relatives with breast cancer, you probably won't find it. Doesn't seem there is much money for such research (no drug company benefit, I guess)