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Breast Cancer Stages - Staging Information

What is Staging?

Staging is the process physicians use to assess the size and location of a patient's cancer. Identifying the cancer stage is one of the most important factors in selecting treatment options. Several tests may be performed to help stage breast cancer including clinical breast exams, biopsy, and certain imaging tests such as a chest x-ray, mammogram, bone scan, CT scan, and MRI scan. Blood tests are used to evaluate a woman's overall health and detect whether the cancer has spread to certain organs often follow imaging tests.

To stage cancer, the American Joint Committee on Cancer first places the cancer in a letter category using the TNM classification system. Cancers are designated the letter T (tumor size), N (palpable nodes), and/or M (metastasis):

T: Tumor Size

The letter T followed by a number from 0 to 4 describes the tumor's size and whether it has spread to the skin or chest wall under the breast. Higher T numbers indicate a larger tumor and/or more extensive spread to tissues surrounding the breast.

  • TX: Tumor cannot be assessed
  • T0: No evidence of a tumor
  • Tis: Cancer may be lobular carcinoma in situ (LCIS), ductal carcinoma in situ (DCIS) or Paget's disease)
  • T1: Tumor is 2 cm or less in diameter
  • T2: Tumor is between 2 and 5 cm in diameter
  • T3: Tumor is more than 5 cm in diameter
  • T4: Tumor is any size, has attached itself to the chest wall and spread to the pectoral (chest) lymph nodes

N: Palpable Nodes

The letter N followed by a number from 0 to 3 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 (lymph nodes were previously removed, etc.)
  • N0: Cancer has not spread to lymph nodes
  • N1: Cancer has spread to the movable ipsilateral axillary lymph nodes (underarm lymph nodes on same side of breast cancer)
  • N2: Cancer has spread to ipsilateral (same side of body as breast cancer) lymph nodes fixed to one another or to other structures under the arm
  • N3: Cancer has spread to the ipsilateral mammary lymph nodes or the ipsilateral (same side of body as breast cancer) supraclavicular lymph nodes

M: Metastasis

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

  • MX: Metastatis cannot be assessed
  • M0: No distant metastasis to other organs
  • M1: Distant metastatis to other organs