Stage 4 bone cancer presents the worst prognosis, cause the cancerous cells have spread from the primary site (bones) to the nearby lymph nodes, lungs and other distant organs.
Any kind of treatment in most of the cases of this stage of disease, is just palliative (ease the symptoms) and isn't curable.
I guess she is treated with chemotherapy and radiotherapy.
You can ask about biotherapy, treatment that boost or restore the ability of the immune system to fight cancer, using antibodies, growth factors, and some of them have a direct anti cancerous effect.
Participation in clinical trials is an important treatment option for many people with bone cancer.