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What Is Sentinel Node Breast Biopsy?

Lymph nodes are located throughout the body. They act as a filtering system. They may become enlarged due to several problems, including infection, or from trapping tumor cells.

A sentinel node is the first lymph a tumor drains into. So it’s the first place that cancer is likely to spread. In breast cancer, the sentinel node is usually one of the axillary lymph nodes in the armpit. A sentinel node biopsy gives the doctors valuable information. And it comes with less risk to you than some other procedures. Prior to the breast resection (lumpectomy or mastectomy), a sentinel node breast biopsy can be performed. During the biopsy, one or more lymph nodes are identified and removed. They are sent to pathology. This happens while the patient is still under anesthesia. The pathologist examines the nodes under a microscope. If the node or nodes indicate that cancer cells are involved, a group of lymph nodes are removed from under the arm. If cancer cells are not identified, then the remaining nodes are left intact. The surgeon then performs the preplanned lumpectomy or mastectomy. (The original procedure that the patient discussed preoperatively with the surgeon.) Identifying, removing, and examining the sentinel node during surgery can eliminate the removal of additional nodes when it is not indicated. 

Note: A more thorough evaluation of the removed node is done after surgery. It’s possible that an initial negative result during surgery may later be found positive. This will require additional surgery to complete a lymph node dissection. 

Three-quarter view of female underarm area showing tumor and sentinel lymph node.

How is the sentinel node found?

There are two methods for finding the sentinel node or nodes. Your surgeon may do one or both of the following:

  • Inject a radioactive blue dye around the tumor. Or it may be injected beneath the pigmented nipple complex of the breast. This is done while the patient is in surgery. Then the dye’s path into the lymph nodes is tracked. The dye collects in the sentinel node.

  • Inject a small amount of a safe radioactive solution near the tumor. A gamma detector is then used to find the “hot spot.” This is the node where the solution has collected.

Understanding the risks

Lymph node surgery involves certain risks. Your surgeon can discuss them with you. These include:

  • Bleeding

  • Fluid collection (seroma)

  • Infection

  • Long-term swelling of the arm (lymphedema)

  • Pain or numbness

Author: StayWell Custom Communications
Last Annual Review Date: 6/1/2017
Copyright © The StayWell Company, LLC. except where otherwise noted.
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