There is not and question that diet alters gene expression (and that includes BRAC and HER 2) (like a graphic equalizer on your stereo you can alter the gene levels in your body - food does that / you can also improve your gene "health" in terms of protecting them from harm)
Gene expression variation alters body function and the risk of cancer.
The difficulty is identifying what is important. There is so much information out there sifting it is not easy.
If you read widely on the subject I think it is difficult to remain unconvinced diet does not play a part. There are lots of mechanisms by which diet influences body function.
It is a complex subject. There will always be exceptions.
You may find this thread interesting. For me it is one of the diet basics and possibly the least appreciated. (understanding and balancing the omega threes and sixes)
http://www.her2support.org/vbulletin...ght=greek+diet
RB