The stage of breast cancer is one of the most important factors in evaluating treatment options. In stage 0, there is no evidence of cancer cells breaking out of the part of the breast in which they started, or of getting through to or invading neighboring normal tissue. In stage I, the tumor measures up to two centimeters and no lymph nodes are involved. In stage II, the tumor measures between two to five centimeters, or cancer has spread to the lymph nodes under the arm on the same side as the breast cancer. In stage III, the tumor in the breast is more than two inches in diameter across and the cancer is extensive in the underarm lymph nodes or has spread to other lymph nodes or tissues near the breast. In stage IV, cancer has spread beyond the breast, underarm and internal mammary lymph nodes to other parts of the body near to or distant from the breast.