Why Are Underarm Lymph Nodes Removed During Breast Cancer Surgery?

Whether you have a lumpectomy or mastectomy for invasive breast cancer, your surgeon will probably remove some of the lymph nodes under your arm to check if the cancer has spread outside the breast.  This procedure is usually done at the same time as the breast surgery.  An incision about two inches long is made under the arm to remove a portion of the fatty tissue containing the lymph nodes.

How many lymph nodes are removed during surgery?

You may talk to other patients and find that each of you had a different number of lymph nodes removed at the time of surgery. Some women have a few nodes removed and others have a dozen or more removed. This is normal. The lymph nodes are encased in the fatty tissue under the arm making it impossible to know the total number in the sample.  Prior to the operation, your surgeon doesn’t plan to remove a specific number of nodes.  The most important factor is the testing performed by pathologists on the nodes after they are removed.

A pathologist examines the lymph nodes under the microscope to see if cancer cells are present.  Lymph nodes that don’t have cancer cells are called negative nodes. Positive lymph nodes (cancer present) may mean you need additional treatment. However, sometimes additional treatment may be recommended even if the lymph nodes are negative.  Your surgeon will talk to you about your results and your treatment plan.

Lymph node removal can result in a swelling of the arm (called lymphedema) on the side of the body where you had surgery.

Updated January 14, 2022

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