Lymph Node Status and Breast Cancer

Front view of female breast anatomy with a lump present
Front view of female breast anatomy with a lump present. Getty Images/Science Picture Co

Lymph Node Status Affects Diagnosis and Treatment:

Lymph node status is an important part of your overall diagnosis. This information is used -- along with characteristics of the primary tumor and whether cancer has spread in a way known as "distant metastases" -- to calculate your prognosis, or long-term outlook after treatment.

Your Lymph System and Breast Cancer:

Breast cancer can travel away from your breast to other parts of your body through your blood and lymph systems. Lymph nodes are gathered in groups in different locations within your body, and those nearest the breast are under your arm and beneath your sternum. Your surgeon will need to check your lymph nodes by touch or with a biopsy, to see if your cancer is well contained, or has spread. A sentinel node biopsy is one such procedure. Lymph nodes can be surgically removed during a biopsy, and examined under a microscope.

Negative and Positive Lymph Nodes:

If your lymph nodes are clear of cancer, they are considered negative or clear, and rated N0. Lymph nodes that contain cancer cells or micrometastasis are considered positive or cancerous, and rated N1, N2, or N3 depending on the number affected and the location.

Rating Positive Lymph Nodes:

  • N1: Cancer is found in 1-3 lymph nodes under the arm or lymph nodes within the breast
  • N2: Cancer is found in 4-9 lymph nodes under the arm or lymph nodes within the breast
  • N3: Cancer is found in 10 or more lymph nodes under the arm, or has spread under or over the collarbone. It may have been found in the underarm nodes as well as lymph nodes within the breast

The staging system most widely used for breast cancer is the TNM system. TNM combines the results of three factors – tumor size (T), lymph node status (N) and metastasis (M). Your TNM score will be considered along with other test results, such as hormone status, and type of breast cancer, in making your treatment plan.

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