Everything you need to know about SLNB (Sentinel Lymph Node Biopsy)

By Medical Expert Team

Aug 25 , 2017 | 2 min read

What is a Sentinel Lymph Node?

A sentinel lymph node is the first lymph node to which cancer cells are most likely to spread from a primary tumor. In certain cases, there can be more than one or two sentinel lymph nodes.

What is a Sentinel Lymph Node Biopsy?

A Sentinel Lymph Node Biopsy (SLNB) is a procedure in which the sentinel lymph node is identified, removed, and examined to determine whether cancer cells are present.

A negative SLNB result suggests that cancer has not developed the ability to spread to nearby lymph nodes or other organs. A positive SLNB result indicates that cancer is present in the sentinel lymph node and may be present in other nearby lymph nodes (called regional lymph nodes) and, possibly, other organs. 

The results from an SLNB can help a doctor to determine the extent of the disease (cancer stage) and develop an appropriate treatment plan.

What happens during an SLNB?

  • A surgeon injects a radioactive substance, a blue dye, or both near the tumor to locate the position of the sentinel lymph node.
  • The surgeon then uses a device that detects radioactivity to find the sentinel node or looks for lymph nodes that are stained with the blue dye.
  • Once the sentinel lymph node is located, the surgeon makes a small incision (about 1/2 inch) in the overlying skin and removes the node.

The removed node is then checked for cancer cells by a pathologist. If the sentinel lymph node is positive for cancer, the surgeon may remove more lymph nodes during a follow-up surgical procedure.
SLNB is usually done at the same time the primary tumor is removed. However, the procedure can also be done either before or after removal of the tumor.

What are the benefits of SLNB?

Sentinel Lymph Node Biopsy help doctors in determining the stage of cancer, estimate the risk of tumor cells having the ability to spread to other parts of the body. It helps to avoid more extensive lymph node surgery in some patients.Additionally, helps avoid/reduce side effects due to extensive lymph node surgery such as lymphedema, numbness, tingling and difficulty moving the affected body part.

Is SLNB associated with other harms?

SLNB, like other surgical procedures, can cause short-term pain, swelling, and bruising at the surgical site and increase the risk of infection.

In addition, some patients may have skin or allergic reactions to the blue dye used in SLNB.

Another potential harm is a false-negative biopsy result—that is, cancer cells are not seen in the sentinel lymph node although they are present and may have already spread to other regional lymph nodes or other parts of the body.

Who are the right candidates for SLNB?

SLNB is most commonly used to help stage breast cancer and melanoma.

In 2014, the American Society of Clinical Oncology released guidelines on sentinel lymph node biopsy. The guidelines say sentinel lymph node biopsy SHOULD be offered even under these circumstances:

  • Breast cancer in which there is more than one tumor, all of which have formed separately from one another (doctors call these multicentric tumors); these types of breast cancers are rare
  • DCIS treated with mastectomy
  • Women who have previously had breast cancer surgery or axillary lymph node surgery
  • Women who have been treated before with chemotherapy or another systemic treatment (treatment before surgery is called neoadjuvant treatment)

Sentinel node biopsy SHOULD NOT be offered under these circumstances:

  • The cancer is 5 cm or larger or locally advanced (cancer has spread extensively in the breast or to the nearby lymph nodes)
  • The cancer is inflammatory breast cancer
  • DCIS treated with lumpectomy
  • Woman is pregnant

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Written and Verified by:

Medical Expert Team