Lymph Node Surgery

Breast cancer has a tendency to spread to the lymph nodes in the axillary or armpit area. As part of a “lumpectomy” or mastectomy, the lymph nodes can either be sampled for spread of cancer or entirely removed if the cancer has already spread.

What are Lymph Nodes?

The lymphatic system is a collection of channels with nodes along their path that ultimately drain into the blood stream. They carry fluid called lymph that is highly concentrated with immune cells to fight cancer and infection all throughout our bodies.1 The lymph nodes are isolated collections of immune cells that can become enlarged or firm when they are fighting infection or cancer in the area that they drain. Lymph nodes that drain the breast are located in the armpit area, called the axilla. When there is cancer in the breast, the lymphatics drain to the lymph nodes where they can be felt if they are enlarged or firm. Determining whether or not there is cancer within the lymph nodes plays an important role in breast cancer staging.2 Almost all cancer spreads to lymph nodes first, before spreading to other areas of the body via the bloodstream.

Lymph Nodes to the Breast

The lymph nodes that drain the breast typically do so in a predictable pattern. They drain from level one to level two, and from level two to level three. Cancer follows this pattern about 97% of the time.

  • Level I: lateral to the pectoralis minor muscle
  • Level II: medial to the pectoralis minor muscle
  • Level III: under the collar bone and between the breasts

Sentinel Lymph Node Dissection

One of the greatest advances in breast cancer surgery is the sentinel lymph node biopsy (SLNB). Sentinel means ‘first’ and since most breast cancer spreads to the lymph nodes before reaching the bloodstream, determining which lymph node drains the cancer first will help determine the extent to which the cancer has spread.3  During this procedure, the first few lymph nodes that are draining the cancer are found and tested to see if they contain cancer cells. The theory is that the cancer cannot spread further than the last positive lymph node.

To do the procedure, your surgeon may decide to use a radioactive tracer alone or in combination with a blue dye. Both can be injected around the location of the tumor, or around the nipple-areolar complex. During your surgery, the surgeon will make a small incision near your armpit and attempt to locate the sentinel lymph nodes. This is done by using a probe that detects that radioactive tracer and the blue dye, which will have turned the sentinel lymph nodes blue. This technique is 95% accurate in detecting sentinel lymph nodes.4 This is considered a minimally invasive procedure and has much less morbidity than the traditional axillary dissection.

Axillary Lymph Node Dissection

If a sentinel lymph node biopsy is found to be positive, or if there is a lymph node in the axilla that is palpable (able to be felt), then an axillary dissection can be done as part of a Modified Radical Mastectomy or as a completion procedure if a mastectomy has already been performed. The axillary dissection removes the lymph nodes in levels I and II. Every woman has a different number of lymph nodes in the breast and axilla. Once removed, a pathologist will examine all of the lymph nodes and determine which have cancerous cells within them. This information is then used to determine the stage of your breast cancer.


1  Andrew H. Ko, M. M. (2002). Everyone’s Guide to Cancer Therapy. Kansas City: Andrews McMeel Publishing.

2 Ibid

3 Ibidte

This article was originally published on July 27,2012 and last revision and update of it was 9/2/2015.