she's having a lung biopsy. Which means the cancer could have spread to her lungs.
I couldn't say that cancer doesn't spread.... but I could definitely say that doctors spend a LOT of money and LOT of time just to do what they do... and they will do everything in their capability to fix what's broken. it's good to hear that she is in good hands.
If she's having a lung biopsy, it's most likely a pro-active procedure the doctors are taking. most cancers can be stopped at a point and cut out.
Breast cancer is among the highest
survival rate and just the fact that she is under doctor supervision and is doing the best for herself that's the best you can do.
Show support to her. You sound like a great friend.