Breast Cancer Stages
When breast cancer is diagnosed, doctors will perform tests, such as MRI and PET scans, to determine if the cancer has spread from the breast to other parts of the body. Cancer is divided into five stages based on its size and whether it has spread to the lymph nodes and/or in other parts of the body. The stage often is not known until after surgery to remove the tumor in the breast and lymph nodes under the arm.
Stage 0 cancer is also referred to as carcinoma in situ. The cancer has not invaded the nearby breast tissue in this stage, but it can become invasive if not treated.
Stage I is an early stage of invasive breast cancer. The tumor is no more than 2 centimeters wide and the cancer cells have not spread beyond the breast.
Stage II is an early detection of a locally advanced cancer.
- The tumor is no larger than 2 centimeters but has spread to the lymph nodes under the arm
- The tumor is between 2 and 5 centimeters and may or may not have spread to the lymph nodes
- The tumor is larger than 5 centimeters but has not spread to the lymph nodes
Stage III cancer is a locally advanced cancer discovered at a later period than Stage II. It is divided into three subunits.
- The tumor is no more than 5 centimeters and has spread to lymph nodes behind the breastbone or lymph nodes under the arm that are attached to each other or to other structures
- The tumor is more than 5 centimeters wide and has spread to lymph nodes behind the breastbone or underarm lymph nodes that are alone or attached to each other or to other structures
In Stage IIIB cancer, the tumor has grown into the chest wall or skin of the breast. It may be associated with swelling of the breast or with lumps in the breast. Stage IIIB cancer may also have spread to lymph nodes behind the breastbone or underarm lymph nodes that are alone or attached to each other or to other structures.
Inflammatory breast cancer is a rare type of cancer in which the breast appears red and swollen due to blocked lymph vessels in the skin of the breast. This cancer is at least Stage IIIB but could be more advanced.
Stage IIIC is a tumor of any size in which:
- The cancer has spread to the lymph nodes behind the breastbone and under the arm
- The cancer has spread to the lymph nodes above or below the collarbone
Stage IV cancer is the most advanced state. This stage is defined by either:
- The cancer has spread to other organs of the body, most often the bones, lungs, liver or brain
- The cancer has spread locally to the skin and lymph nodes inside the neck, near the collarbone