The number staging system for breast cancer divides breast cancers into 4 stages, from 1 to 4. Stage 1 is the earliest stage and stage 4 means the cancer has spread to another part of the body.
Stage 1 breast cancer means that the cancer is small and only in the breast tissue, or it might be found in lymph nodes close to the breast.
Stage 2 breast cancer means that the cancer is either in the breast or in the nearby lymph nodes or both. It is an early stage breast cancer.
Stage 3 means that the cancer has spread from the breast to lymph nodes close to the breast or to the skin of the breast or to the chest wall.
Stage 4 breast cancer means that the cancer has spread to other parts of the body.