Understanding Breast Cancer Staging

Understanding the stages of breast cancer can be complicated, so when visiting a specialist cancer centre, such as Cancer Treatment Mexico, it is important to make sure you ask plenty of questions in order to fully understand exactly the stage your cancer is in.

To stage cancer, the American Joint Committee on Cancer, first places the cancer in a letter category using the tumour, nodes, metastasis (TNM) classification system. The stage of a breast cancer describes its size and the extent to which it has spread. The staging system ranges from stage 0 to stage IV according to tumour size, lymph nodes involved, and distant metastasis.

T indicates tumour size. The letter T is followed by a number from 0 to 4, which describes the size of the tumour and whether it has spread to the skin or chest wall under the breast. Higher T numbers indicate a larger tumour and/or more extensive spread to tissues surrounding the breast.

TX: The tumour cannot be assessed.

T0: No evidence of a tumour is present.

Tis: The cancer may be LCIS, DCIS, or Paget disease.

T1: The tumour is 2 cm or smaller in diameter.

T2: The tumour is 2-5 cm in diameter.

T3: The tumour is more than 5 cm in diameter.

T4: The tumour is any size, and it has attached itself to the chest wall and spread to the pectoral (chest) lymph nodes.

N indicates palpable nodes. The letter N is followed by a number from 0 to 3, which indicates whether the cancer has spread to lymph nodes near the breast and, if so, whether the affected nodes are fixed to other structures under the arm.

NX: Lymph nodes cannot be assessed (eg, lymph nodes were previously removed).

N0: Cancer has not spread to lymph nodes.

N1: Cancer has spread to the movable ipsilateral axillary lymph nodes (underarm lymph nodes on the same side as the breast cancer).

N2: Cancer has spread to ipsilateral lymph nodes (on the same side of the body as the breast cancer), fixed to one another or to other structures under the arm.

N3: Cancer has spread to the ipsilateral mammary lymph nodes or the ipsilateral supraclavicular lymph nodes (on the same side of the body as the breast cancer).

M indicates metastasis. The letter M is followed by a 0 or 1, which indicates whether the cancer has metastasized (spread) to distant organs (eg, lungs or bones) or to lymph nodes that are not next to the breast, such as those above the collarbone.

MX: Metastasis cannot be assessed.

M0: No distant metastasis to other organs is present.

M1: Distant metastasis to other organs has occurred.