Zometa

Hi,
My mother has just finished treatment with chemo and rads.
She is trippel negative. She is 56 years old.
The onc is recommending zometa every 6 months.
There is a lot of side effects, and the studies seems a bit uncertain when it comes to preventing spread to the bones. I have read that trippel negative spread more to lung/liver than the bones.
I have also read that, its used as adjuvant treatment in postmensual women. She doesnt have her period any more because of chemo, but she had her last period 6 months ago.
Are zometa given if you are trippel negative as adjuvant treatment? And what about if you are boarder line per/post mensual?
I would like to hear from others what your onc is recommending regarding zometa.