Stage 1, the tumor is less than 2 cm in diameter and does not appear to have spread beyond the breast.
Stage 2, the tumor is larger than 2 cm in diameter and may or may not have spread to the lymph nodes under the arm.
Stage 3, (also called locally advanced cancer) the tumor is larger than 5 cm in diameter or has spread to the underarm lymph nodes, or has spread to other tissue near the breast.
Stage 4, the cancer has spread to other organs of the body, such as bones, lungs, or to lymph nodes not near the breast.