Sorry I haven't been expressing appreciation for all the good will. It's kinda funny, but I feel like an attention whore reading them. They're appreciated nonetheless.
Mom had her follow-up appointment and go the official full-blown biopsy results yesterday. It went about as well as it possibly could (not counting "We fucked up, you don't actually have cancer at all. Please don't sue us.")
Needing chemo is very unlikely, which I think was the big cloud over Mom's head since this mass was farther along than the one from 20 years ago. 20 years ago the cancer wasn't even a mass, it was "nodules." She'll have either a lumpectomy with radiation or another mastectomy, probably without even radiation. They'll check her lymph nodes and if they're fine she's done.
Either way the procedure shouldn't be nearly as physically taxing as last time around. It's not scheduled yet, but she could have the procedure before Christmas and be "Ok" by Christmas. That seems downright miraculous to me.