The stage of the cancer helps you and your doctor:. Breast cancer stage is usually expressed as a number on a scale of 0 through IV — with stage 0 describing non-invasive cancers that remain within their original location and stage IV describing invasive cancers that have spread outside the breast to other parts of the body. Your pathology report will include information that is used to calculate the stage of the breast cancer — that is, whether it is limited to one area in the breast, or it has spread to healthy tissues inside the breast or to other parts of the body. Your doctor will begin to determine this during surgery to remove the cancer and look at one or more of the underarm lymph nodes, which is where breast cancer tends to travel first.
Classifying your breast cancer by stage helps predict your chance of cure and helps identify the best treatment options for your particular cancer. After discovering that you have breast cancer, your doctor will decide what additional tests may be helpful to find out if the disease has spread outside the breast. Called breast cancer staging, this process provides information about the extent of the disease. Your breast cancer stage helps your doctor determine which treatments are most likely to benefit you. The stages of breast cancer are indicated using Roman numerals ranging from 0 to IV, with 0 indicating cancer that is noninvasive or contained within the milk ducts. Greater numerals indicate a more invasive cancer. By stage IV breast cancer, also called metastatic breast cancer, the cancer has spread to other areas of the body.
Stage 3 cancer means the breast cancer has extended to beyond the immediate region of the tumor and may have invaded nearby lymph nodes and muscles, but has not spread to distant organs. Although this stage is considered to be advanced, there are a growing number of effective treatment options. The difference is determined by the size of the tumor and whether cancer has spread to the lymph nodes and surrounding tissue.
T followed by a number from 0 to 4 describes the main primary tumor's size and if it has spread to the skin or to the chest wall under the breast. This includes inflammatory breast cancer. N followed by a number from 0 to 3 indicates whether the cancer has spread to lymph nodes near the breast and, if so, how many lymph nodes are involved. Lymph node staging for breast cancer is based on how the nodes look under the microscope, and has changed as technology has improved. Newer methods have made it possible to find smaller and smaller collections of cancer cells, but experts haven't been sure how much these tiny deposits of cancer cells affect outlook.