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Breast Cancer Health Center

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Breast Cancer, Lymph Node Biopsy, and Dissection

If you’ve been diagnosed with breast cancer, doctors will need to know if the cancer has spread beyond your breast. To find this out, they’ll remove one or more of your lymph nodes under the arm on the side where the cancer was found.

This is called lymph node biopsy and dissection. The procedure has two main purposes.

  1. It allows the surgeon to figure out what stage the cancer is in by learning how far it has spread.
  2. It removes the breast cancer that may have spread into the armpit.

There are two ways for doctors to remove and test lymph nodes:

Sentinel node biopsy. The surgeon injects a special blue dye, a radioactive substance, or both into your breast in the area of the tumor. That helps him determine which lymph nodes are the first to receive drainage from the breast -- these nodes would potentially be the first to be invaded by cancer cells. One to three sentinel nodes are usually removed and tested for cancer. If the results are negative, the cancer hasn’t spread to the lymph nodes.

Axillary node dissection. At least six of the lymph nodes under your arm are removed and sent to a lab to be checked for cancer. This method is a very reliable way to check the extent of your cancer. But it can take a while to recover, and it can have complications like lymphedema  (swelling of the arm) or nerve damage.

If you have an axillary node dissection, a drain will be placed under your arm to remove fluids that may build up and cause swelling. Then the wound is then closed.

After the procedure, you’ll likely need to stay in the hospital 1 to 2 nights. If you had reconstructive surgery at the same time, your stay will be longer. You may go home with the drain in place. Your doctor will remove it a few days later.

It’s common to have some swelling. You can take pain medication as needed. Complete healing takes about 6 weeks.

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