1. Briefly explain the staging used in breast cancer.
2. Are all breast cancer malignant?
3. Is there really benign breast cancer?
1) Please read this explanation of staging breast cancer.
2) Cancer is by definition malignant; there's no such thing as benign cancer. There IS such a thing as invasive or infiltrating vs. non-invasive cancer. Invasive is where the cancer has broken through its initial starting place (e.g., milk ducts, lobules) and gone into surrounding tissue; about 80% of women diagnosed with breast cancer have invasive breast cancer. The remainder have non-invasive (also called "in situ") cancer, sometimes known as a "pre-cancer" as some doctors don't believe cells are cancerous until they spread.
Hope this helps - PJH