As my Dr.told me when he found a suspicious lump: "Breast cancer is VERY treatable nowadays." So, we will think positive for her and believe she will be a survivor of the disease.
Good thoughts for her. Chemo and radiation are rough on the body, so I hope she has a ton of support at home. Also, she should see if her hospital has support groups and/or classes. My mom's first round of chemo for her ovarian cancer was a group thing: a whole group of women who had chemo at the same time. They would have group therapy/question answer sessions, they would have people come in and teach them how to do make up while going through chemo so that it didn't look weird, they had wig trying on sessions, and after each round of chemo they would leave with a little gift (usually an ovarian cancer pin, or something of the sort). I think it was a wonderful program to have.
Also if she knows anyone else who has gone through breast cancer treatments, tell her to reach out to them. Talking it out with someone who has been through it before, who ISN'T family or super close friend, can sometimes be more helpful than trying to talk about it with family (as it can be emotionally draining).
So plenty of good thoughts, tell her to seek out some support services, and she'll fight through it and come out on the winning end.
"All changes, even the most longed for, have their melancholy; for what we leave behind us is a part of ourselves; we must die to one life before we can enter another." -Anatole France