Breast cancer stages: 0, I, II, III, IV: Cancer stage is based on the size of the tumor, whether the cancer is invasive or non-invasive, whether lymph nodes are involved, and whether the cancer has spread beyond the breast.
Stage 0- is used to describe non-invasive breast cancers, such as DCIS and LCIS. In stage 0, there is no evidence of cancer cells or non-cancerous abnormal cells breaking out of the part of the breast in which they started, or of getting through to or invading neighboring normal tissue.
Stage 1- describes invasive breast cancer (cancer cells are breaking through to or invading neighboring normal tissue) in which the tumor measures up to 2 centimeters and no lymph nodes are involved.
Stage 2- Stage 2 is divided into subcategories known as 2A and 2B.
Stage 2A- No tumor can be found in the breast, but cancer cells are found in the axillary lymph nodes (the lymph nodes under the arm).
Stage 2B- the tumor is larger than 2 but no larger than 5 centimeters and has spread to the axillary lymph nodes.
Stage 3- Stage III is divided into subcategories known as IIIA, IIIB, and IIIC.
Stage 3A- no tumor is found in the breast. Cancer is found in axillary lymph nodes that are clumped together or sticking to other structures, or cancer may have spread to lymph nodes near the breastbone.
Stage 3B- the tumor may be any size and has spread to the chest wall and/or skin of the breast
Stage 3C- there may be no sign of cancer in the breast or, if there is a tumor, it may be any size and may have spread to the chest wall and/or the skin of the breast, and the cancer has spread to lymph nodes above or below the collarbone.
Stage 4- the cancer has spread to other organs of the body -- usually the lungs, liver, bone, or brain.