The American Joint Committee on Cancer (AJCC) created a way to determine how much cancer is in your body, where it is located, and what subtype of cancer you have. This is called staging. Based on testing, your cancer will be assigned a stage. Staging is needed to make treatment decisions.
Cancer staging is often done twice.
- Clinical stage (c) is the rating given before any treatment. It is based on a physical exam, biopsy, and imaging
- Pathologic stage (p) or surgical stage is determined by examining tissue removed during an operation
The tumor, node, metastasis (TNM) system is used to stage breast cancer. In this system, the letters T, N, and M describe different areas of cancer growth. Based on cancer test results, your doctor will assign a score or number to each letter. The higher the number, the larger the tumor or the more cancer has spread. These scores will be combined to assign cancer a stage. A TNM example might look like this: T2, N1, M1.
- T (tumor) – Size of the main (primary) tumor
- N (node) – If cancer has spread to nearby (regional) lymph nodes
- M (metastasis) – If cancer has spread to distant parts of the body or metastasized
Number stages range from stage 1 to stage 4, with 4 being the most advanced. Doctors write these stages as stage I, stage II, stage III, and stage IV.
Stage 0 is noninvasive
Noninvasive breast cancer is rated stage 0. DCIS is found only in the ducts (Tis). It has not spread to the surrounding breast tissue, lymph nodes (N0) or distant sites (M0).
Stages 1, 2, and 3 are invasive
Invasive breast cancer is rated stage 1, 2, or 3. It has grown outside the ducts, lobules, or breast skin. Cancer might be in the axillary lymph nodes.
Stage 4 is metastatic
In stage 4 breast cancer, cancer has spread to distant sites. Your first diagnosis can be stage 4 metastatic breast cancer or it can develop from earlier stages.