How are the stages of breast cancer determined?

Dr. Deanna J. Attai, MD

The stages of breast cancer are determined by the size of the tumor and if it has spread to underarm lymph nodes or other areas of the body. The stages include:

  • Stage 0: noninvasive breast cancer.
  • Stage I: invasive cancer confined to the breast with a tumor up to 2 cm in size. No spread to the underarm lymph nodes.
  • Stage II: invasive cancer with a tumor 2 to 5 cm in size or with a tumor less than 5 cm in size with spread to the underarm lymph nodes.
  • Stage III: invasive cancer with a tumor bigger than 5 cm in size, or with spread to multiple underarm lymph nodes, skin or muscle.
  • Stage IV: invasive breast cancer that has spread to other organs such as the lungs, liver, bone or brain.

Clinical staging of breast cancer involves an assessment of the size of the tumor and whether or not lymph glands under the arm (axilla) appear to be involved. It is difficult for doctors to accurately assess node involvement on the basis of a physical examination or noninvasive testing. For that reason, initial preoperative clinical staging is considered preliminary. Final pathologic staging occurs after surgical results are available. Surgery results may change the initial clinical stage.

The majority of patients present with early-stage breast cancer. Staging of breast cancer is as follows:

  • Stage 0: Noninvasive breast cancer
  • Stage I: Tumors less than 2 cm (~ 1 inch) without involved nodes
  • Stage II: Tumors less than 2 cm with involved nodes, tumors between 2-5 cm with or without involved nodes and tumors greater than 5 cm without involved nodes
  • Stage III: Tumors greater than 5 cm with involved nodes, tumors that are locally advanced (e.g., involvement of the skin or underlying muscle) and tumors with many involved nodes
  • Stage IV: Tumors that have spread outside the region of the breast (metastatic)

It is unusual for breast cancer to have already spread at the time of the initial diagnosis. However, after the diagnosis of breast cancer has been made, it is important to determine this. X-rays and blood tests are typically ordered. Not all patients require all these tests. Your doctor’s assessment of how early or advanced the tumor is and whether or not symptoms are present will determine the need for various studies. Common tests ordered include a chest X-ray, laboratory blood studies to include an assessment of liver function, bone scan, CT scans and PET scans. If abnormalities are found on initial testing, further testing may be needed.

Whenever there is diagnosis of invasive cancer, it is necessary to measure the extent of the cancer, which is called staging. The breast cancer stage is based on three parameters: the size of the tumor in the breast, the number of lymph nodes involved by the cancer and if there is disease present elsewhere in the body (distant metastasis). For staging breast cancer, some tests may be indicated for your case, such as CT combined or not with PET scan, bone scan or a brain scan. In some cases, all of the tests may be required. They may be done prior to surgery or after the operation, when more information about the size of the tumor and lymph node involvement becomes available. Patients diagnosed with large breast tumors and/or presenting with more than three positive lymph nodes or cancer invasion into the skin and chest wall or inflammatory breast cancer (even without other significant symptoms) should consider the scans mentioned below for proper staging. For clinical early stage disease, the use of further scans will be triggered by patient’s complaint or abnormal blood laboratory tests. The most common sites of metastatic (spread) breast cancer are the bones, lungs, liver and brain, in an isolated form or multiple sites.
If breast cancer is found, more tests will be done to find out the size and extent of the cancer in the breast and to determine whether the cancer has spread from the breast to other parts of the body. This is called staging. The stages range from Stage 0 (a very early cancer) to Stage IV (the cancer has spread to other organs of the body). It may also be classified as recurrent (the cancer has come back after being treated), according to the American Joint Committee on Cancer, seventh edition.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.