Cancer cells can spread from the breast to other parts of the body..This spread is called metastasis..
Understanding how a type of cancer usually grows and spreads helps your healthcare team plan your treatment and future care...
https://breastcancernow.org/in....formation-support/fa

Secondary breast cancer in the bone
breastcancernow.org

Secondary breast cancer in the bone

Breast cancer that has spread to the bones is known as secondary or metastatic breast cancer in the bone.