Staging is the most critical requirement for deciding on the most accurate and effective treatment once the finding of breast cancer is confirmed.

Simply put, staging is a way of investigating whether cancer cells have spread into the breast or elsewhere in the body.

There are two types of staging in breast cancer, clinical staging and pathological staging.

Clinical staging: Staging using physical examination and imaging techniques including breast and axilla.

Pathologic Staging: In addition to clinical staging, pathologic examination of the excised breast tissue and axillary lymph nodes is performed.

The TNM system is used to stage cancer.

T indicates tumor. (Its size indicates how far it has spread into the breast or organs).

N indicates the state of the lymph nodes.

M indicates whether the cancer has metastasized (spread).

Some numbers and letters after T, N and M are used for details about the tumor, lymph node and metastasis.

The two most important factors in breast cancer prognosis:

• Number of axillary lymph node involvement
• Metastatic disease.

In the staging system, the stage is indicated by a number between 0 and 4.

Stage 0 (carcinoma in situ): Carcinomas in situ are cancers that have remained in situ and have not spread to the surrounding area.

Stage 1 The tumor size is 2 cm or less and the cancer cells have not spread outside the breast (to the lymph nodes).

Stage 2A The tumor is 2 cm or smaller and has spread to the axillary lymph nodes or

the tumor is larger than 2 cm and smaller than 5 cm and has not spread to the axillary lymph nodes.

Stage 2B Tumor is larger than 2 cm, smaller than 5 cm and has spread to the axillary lymph nodes or

the tumor is larger than 5 cm but has not spread to the axillary lymph nodes.

Stage 3A The tumor is 5 cm or smaller and has spread to the axillary lymph nodes and the lymph nodes are adherent to surrounding tissues or to each other, or the tumor is larger than 5 cm and has spread to the axillary lymph nodes and the lymph nodes are adherent to surrounding tissues or to each other.

Stage 3B The tumor can be any size and has spread to tissues adjacent to the breast (skin or chest wall, ribs or muscles in the chest wall) or the breast has an orange peel appearance,

tumor cells have spread to the lymph nodes within the rib cage (under the ribs), inflammatory breast cancer is considered stage 3B.

Phase 3C The tumor may be of any size, it may have spread to tissues adjacent to the breast (skin or chest wall, ribs or muscles in the chest wall), tumor cells have spread to both the axillary lymph nodes and the lymph nodes in the rib cage (under the ribs), or the tumor has spread to the lymph nodes below the collarbone, with or without additional spread to the axillary lymph nodes, tumor cells have spread to the lymph nodes above the collarbone, with or without spread to the lymph nodes in the axilla and rib cage.

Stage 4 Cancer cells have spread beyond the breast to other parts of the body (such as the bones, lungs, liver or brain).