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Breast Cancer Basics

Staging

Breast cancer staging is an important part of the pathology report that takes into consideration whether your cancer is invasive (cancer cells have broken through to the surrounding tissues), the size of your tumour, whether the cancer has spread to the nearby lymph nodes and whether the cancer has spread to other areas in your body. It is used most commonly to guide treatment decisions.

Certain terms are often used to discuss the stages of breast cancer. Most typically this includes:

Local - describes cancers remaining within the breast.

Regional - cancers with nearby lymph node involvement.

Distant - describes cancers that have spread to other parts of the body.

Breast cancer is staged using the ‘TNM’ system, which stands for Tumour, Nodes and Metastases. This system considers the size of the tumour, the number of lymph nodes that are affected, if any, and the other parts of the body to which the cancer has spread (metastasized), if any.  Based on this information it is given a stage 0-IV.  For example, a classification of T1N0M0 means a small, early-stage breast cancer with no lymph node involvement and no metastases (stage I). A classification of T4N3M1 means an advanced metastatic breast cancer with a large tumour in the breast and cancer in many lymph nodes (stage IV).

  • Stage 0 means that the cancer cells are non-invasive (cancer cells have not broken through to the normal surrounding tissues) and have not spread.
  • Stage 1 involves a small local (remaining within the breast) invasive tumour without lymph node involvement.
  • Stage II describes invasive, larger tumours which may involve spread to the nearest lymph nodes.
  • Stage III indicates invasive cancers with considerable lymph node involvement.
  • Stage IV means the cancer has spread to other parts of the body (metastasized). Visit our Living with Metastatic Breast Cancer for more information.

If you have additional questions about breast cancer staging in relation to your breast cancer, connect with your doctor. 

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