I believe you are referring to breast cancer that has moved beyond the breast and into the bone. This is called bone metastasis. Bone metastasis is cancer that started in another part of the body and spread to the bone. Bone metastasis is not the same as cancer that starts in the bone (called primary bone cancer). Bone metastases are much more common than primary bone cancer.
Or have you been diagnosed with a second primary cancer of the bone?