How is stage iv breast cancer different from stage iii breast cancer?

Distant Spread: Stage IV breast cancer means that the cancer has spread to another organ such as the lungs, liver, or bone. Stage III cancer describes a cancer that is large, has grown into the chest wall or skin of the breast, and/or is extensively involving the adjacent lymph nodes.

Location: In stage iii, the cancer still hasn't spread far beyond the breast and nearby lymph nodes. However, in this stage there typically are many lymph nodes involved or the tumor is so large it extends to the chest wall or involves the skin of the breast. stage IV breast cancer has spread to distant sites of the body.