Breast Cancer Staging

Breast Cancer Staging
Staging is the process of determining the extent of the cancer and its spread in the body. Together with the type of cancer, staging is used to determine the appropriate therapy and to predict chances for survival.

To determine if the cancer has spread, several different imaging techniques can be used.
  • Chest X-ray: It looks for spread of the cancer to the lung.
  • Mammograms: More detailed and additional mammograms provide more images of the breast and may locate other abnormalities.
  • Computerized tomography (CT scan): These specialized X-rays are used to look at different parts of your body to determine if the breast cancer has spread. It could include a CT of the brain, lungs, or any other area of concern.
  • Bone scan: A bone scan determines if the cancer has spread (metastasized) to the bones. Low level radioactive material is injected into the bloodstream, and over a few hours, images are taken to determine if there is uptake in certain bone areas, indicating metastasis.
  • Positron emission tomography (PET scan): A radioactive material is injected that is absorbed preferentially by rapidly growing cells (such as cancer cells). The PET scanner then locates these areas in your body.
  • Staging system: This system is used by your health care team to summarize in a standard way the extent and spread of your cancer. This staging can then be used to determine the treatment most appropriate for your type of cancer.
The most widely used system in the U.S. is the American Joint Committee on Cancer TNM system.

Breast Cancer Staging

Besides the information gained from the imaging tests, this system also uses the results from surgical procedures. After surgery, a pathologist looks at the breast cancer and associated lymph nodes under the microscope. This information gained is incorporated into the staging as it tends to be more accurate than the physical exam and X-ray findings alone.

TNM staging:
T: This describes the size of the tumor. It is followed by a number from 0 to 4. Higher numbers indicate a larger tumor or greater spread:
  • TX: Primary tumor cannot be assessed 
  • T0: No evidence of primary tumor 
  • Tis:Carcinoma in situ 
  • T1: Tumor is 2 cm or less across 
  • T2: Tumor is 2 cm to 5 cm 
  • T3: Tumor is more than 5 cm 
  • T4: Tumor of any size growing into the chest wall or skin.
N: This describes the spread to lymph nodes near the breast. It is followed by a number from 0 to 3.
  • NX: Nearby lymph nodes cannot be assessed (for example if they have previously been removed). 
  • N0: There has been no spread to nearby lymph nodes. In addition to the numbers, this part of the staging is modified by the designation "i+" if the cancer cells are only seen by immunohistochemistry (a special stain used by pathologists during microscopic examination) and "mol+" if the cancer could only be found using PCR (special laboratory detection technique to detect cancer at the molecular level).
  • N1: Cancer has spread to one to three axillary lymph nodes (underarm lymph nodes) or tiny amounts of cancer are found in internal mammary lymph nodes (lymph nodes near breastbone).
  • N2: Cancer has spread to four to nine axillary lymph nodes or the cancer has enlarged the internal mammary lymph nodes. 
  • N3: Any of the conditions below:
Cancer has spread to 10 or more axillary lymph nodes with at least one cancer spread larger than 2 mm.

Cancer has spread to lymph nodes under the collar bone (clavicle) with at least one area of cancer spread greater than 2 mm.
  • M: This letter is followed by a 0 or 1, indicating whether the cancer has spread to other organs.
  • MX: Metastasis cannot be assessed. 
  • M0: No distant spread is found on imaging procedures or by physical exam. 
  • M1: Spread to other organs is present.
Once the T, N, and M categories have been determined they are combined into staging groups. There are five major staging groups, stage 0 to stage IV, which are subdivided into A and B, or A and B and C, depending on the underlying cancer and the T, N, and M scale.

Cancers with similar stages often require similar treatments. Breast Cancer Staging from best information.