What is invasive cancer of the breast means?

Invading the tissues: This means that the breast cancer has gone past any containing membrane(s) and/or capsules and into the surrounding soft tissue. It usually travels to the lymph nodes, from which it can metastasize to other organs in the body, like the lung, bones, and liver. This is usually treated with combination therapy (surgery, radiation, and chemotherapy).

Capable of Spreading: Most breast cancers begin in the milk-producing lobules or milk-carrying ducts of the breast. A breast cancer is considered "in situ" when it is contained w/in these structures. If it grows outside the lobule or duct into the adjacent breast, it is called "infiltrating" or "invasive", since the cells may enter the lymphatic circulation or bloodstream and (potentially) travel anywhere in the body.

Beyond the ducts: This means the cancer cells have developed the ability to leave the milk ducts and travel into the breast and possibly beyond.