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About Breast Cancer>Treatments>Surgery > Lymph node surgery

Lymph node surgery

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If you have an invasive breast cancer, your surgeon will need to check for cancer in one or several lymph nodes in the armpit on the side of the body where the cancer was found. Lymph nodes are organs that help the body filter out waste, bacteria and damaged cells.

This surgery will usually be done at the same time as your breast surgery. What your doctors learn will help them find out the stage of the cancer and how best to treat it.

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Sentinel lymph node biopsy

To find out whether cancer is in the lymph nodes, a doctor removes a few lymph nodes from your underarm where the cancer is most likely to spread first. These are called the sentinel nodes.

Sentinel node biopsy usually happens at the same time as lumpectomy or mastectomy surgery. If you are having mastectomy and breast reconstruction surgery at the same time, sentinel node biopsy will be a part of the same operation.

Before surgery, your doctor will inject a blue dye and/or a radioactive substance into your breast. At the time of surgery, the surgeon will look for the lymph nodes that have taken up the dye and remove them.

Sentinel lymph node biopsy is usually not offered if you have:

If these things are true for you, your doctor may recommend an axillary lymph node dissection. If you have DCIS and plan to have a lumpectomy, you may not need any lymph node procedure.

Any time lymph nodes are removed, there is a risk of lymphedema, a swelling of the tissues under the skin that can become a chronic condition if not treated early. Lymphedema can happen in the arm, hand, or breast on the same side where lymph nodes are removed. The risk increases when more lymph nodes are removed, but there is still some risk with removing a few nodes during sentinel node biopsy.

If sentinel node biopsy has been recommended for you, talk with your care team about risk reduction steps you can take. Some cancer centers offer baseline arm measurements and monitoring technology, such as bioimpedance spectroscopy, which uses a low-level electrical current to confirm signs of lymphedema at a stage when it may be reversible. Learn more on the lymphedema page.

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Axillary lymph node dissection

If cancer is found in a lymph node or nodes after a sentinel node biopsy, you may need an axillary lymph node dissection, or removal of most of the lymph nodes in the armpit. An axillary lymph node dissection will help your doctors stage the cancer and recommend treatment.

Axillary dissection is a more extensive surgery than sentinel node biopsy. It has a higher risk for side effects such as shoulder stiffness and lymphedema, a painful swelling condition. If lymphedema develops after underarm lymph node surgery, symptoms may occur in the hand, arm, trunk, or breast on the same side.

To reduce the risk of unnecessarily removing too many lymph nodes (and increasing the risk of lymphedema), doctors may place a localization marker in the specific lymph node or nodes that need to be removed for a more precise surgery.

There are also other ways to reduce the risk of lymphedema. As you are planning surgery with your doctor, ask about getting baseline arm measurements before the date of your operation. A baseline measurement helps your care team know what is normal for your arm size. This helps your team monitor for any changes after surgery.

Tools such as bioimpedance spectroscopy can provide a baseline assessment and help detect lymphedema at an early stage, when it is potentially reversible. Learn more on the Lymphedema page.

If lymphedema develops, your doctor may refer you to a physical or occupational therapist or a lymphedema specialist.

Axillary node dissection may not be recommended if you:

  • Have no cancer in the lymph nodes
  • Have cancer in one or two lymph nodes, and you plan on having a lumpectomy followed by radiation therapy
  • Plan to have radiation to the armpit area

Targeted axillary lymph node dissection after neoadjuvant chemotherapy

If imaging shows that cancer may be in an underarm lymph node, a core needle biopsy can be performed on the node. If a biopsy confirms cancer is in the node and your treatment plan includes chemotherapy to try to shrink the cancer before surgery (neoadjuvant chemotherapy), your surgeon can perform a procedure called targeted axillary dissection.

Targeted axillary dissection uses a combination of sentinel node biopsy and the removal of one cancerous axillary node to help prevent false-negative lymph node results after neoadjuvant chemotherapy. This technique also reduces the risk of lymphedema because fewer nodes are removed.

To prepare for a targeted axillary dissection, doctors use a needle or other device to place a marker in the cancerous lymph node before chemotherapy is given. The marker may be a magnetic or radioactive seed, a radar reflector, or other marker that can be located using a wireless probe.

After chemotherapy is finished, the wireless probe is used to find the marker and remove it along with the lymph node. During the same procedure, sentinel node biopsy is performed.

Targeted axillary dissection after neoadjuvant chemotherapy reduces the risk of false-negative lymph node status results from more than 10% down to about 2%.

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Questions to ask your doctor

Here are some key questions to consider before surgery:

  • Will I have a sentinel lymph node biopsy or axillary dissection?
  • Why do you recommend one surgery over the other?
  • What are the risks for short- and long-term side effects?
  • Should I get neoadjuvant therapy, treatment before surgery?
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Side effects of lymph node surgery

Lymph node surgery is an important part of diagnosing, staging, and treating breast cancer. But lymph node surgery can have serious, long-term side effects, such as:

  • Loss of sensation under the arm and in the back of the arm
  • Shoulder and armpit stiffness
  • Lymphedema

Talk with your doctors about these risks as you are planning your surgery:

  • Ask about a lymphedema screening and monitoring plan that starts before surgery with a baseline arm measurement.
  • Ask about stretching exercises you can do after lymph node surgery to reduce the risk of stiffness and lymphedema.

Learn more on the Lymphedema page.

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Reviewed and updated: August 24, 2025

Reviewed by: Anna Mazor, DO

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