Invasive cancer is cancer that has spread from inside your breast duct or lobule to invade other parts of your breast. When breast cancer spreads to other parts of your body, this is called "metastasis." The cancer cells circulate in your blood until they invade a body part and grow there. They often settle in the liver, lungs, or bones. Treatment for invasive cancer usually requires both local and systemic treatments.

Local treatment (shown on left) is done to eliminate the cancer that is in your breast itself, and often consists of the removal of the cancer tissue combined with local radiation therapy.

Systemic treatment (shown on right) is done to treat possible or actual tumor cells (no matter where they are) that may have spread. Systemic treatment fights cancer all over your body, not just in your breast.