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Sentinel Lymph Node Biopsy

What Happens When the Sentinel Node Is Found To Be Cancerous?

After the surgeon removes the sentinel node(s), a pathologist will perform a preliminary examination of the nodes to determine whether they contain cancer cells. The sentinel lymph nodes will be classified as negative (no cancer), positive (contain cancer), or indeterminate.  However, this preliminary report is followed by close examination and the final pathology report.

If the sentinel node is determined to be cancerous while the patient is still in surgery, the surgeon will usually remove additional lymph nodes in the axilla.   However, the final pathology report is not available until after the surgery has been completed, and patients should schedule a follow-up visit with the surgeon to discuss the final report.  Sometimes, the final report indicates a positive (cancerous) sentinel node that was not seen on preliminary review.  If this occurs, then additional surgery may be necessary to remove more nodes for examination.

What Are the Side Effects of a Sentinel Lymph Node Biopsy?

Because sentinel lymph node biopsy involves removal of fewer lymph nodes than a standard axillary lymph node dissection, the potential for side effects such as lymphedema is much lower. Many patients who undergo sentinel node biopsy do not experience any side effects. However, some patients report post-operative pain, nerve damage, or lymphedema after the procedure. These symptoms occur more frequently when additional lymph nodes are removed along with the sentinel node.

The blue dye that is injected will turn the urine green for about 24 hours and may cause a temporary bluish discoloration of the breast skin. The radioactive energy from the technetitum-99 injection dissipates on its own, and some of the radiation is eliminated through urine or bowel movement. The result is that the radioactive material is only in the patient for a short time. Once the energy is eliminated, patients will no longer carry the radioactivity. The levels of radiation involved in a sentinel node biopsy are considerably lower than a patient would receive in a conventional x-ray study, bone scan or CT scan.

Most women who undergo sentinel node biopsy spend one day or less in the hospital. Occasionally, sentinel node biopsy may be performed on an outpatient basis.

Is Sentinel Node Biopsy Accurate?

Many surgeons agree that breast cancer may be accurately staged without having to remove any lymph nodes besides the sentinel node. Nevertheless, researchers are finding that a low percentage of sentinel node biopsy results can turn out to be “false negatives.”  That is, the sentinel nodes do not contain cancer when, in fact, the patient’s other axillary lymph nodes do contain cancer. 

This has been an important teaching point in many advanced courses presented to physicians who perform sentinel node biopsy.  If a physician is uneasy about the looks of a sentinel node, even though it is not cancerous, the surgeon will typically remove additional lymph nodes to check their status.

The scenario of a negative (non-cancerous) sentinel node and positive (cancerous) additional nodes in a patient can occur for several reasons, including:

  • The timing of the dye injections
  • The type of dye/tracers used
  • The presence of more than one sentinel node
  • The way in which the initial node was sectioned or stained in the pathology lab

The American College of Surgeons Oncology Group recommends that physicians perform at least 30 sentinel lymph node biopsies followed by complete axillary node dissection, with an 85% success rate in identifying the sentinel lymph node(s) and a 5% or lower false positive rate. After they have accomplished this, physicians can then perform sentinel lymph node biopsy without a back-up axillary node dissection. According to the Canadian committee, physicians who have performed less than 30 sentinel lymph node biopsies should only perform the procedure as part of a clinical trial. Patients who are considering sentinel lymph node biopsy should ask their surgeon how many procedure he/she has performed and his/her success rate.

The committee also recommended that all patients be fully aware of the potential benefits and challenges of sentinel lymph node biopsy, including what is known and not known about the procedure. In particular, patients should be aware that there is a small chance (usually less than 10%) that the results of the sentinel lymph node biopsy can be inaccurate (false negatives); that is, there is no cancer in the sentinel nodes but cancer exists in other axillary lymph nodes. Missing these cancer cells can affect a patient's treatment after surgery and the chances that breast cancer may return.

To address some of the challenges of sentinel lymph node biopsy, the committee recommended guidelines for both physicians and patients:

  • Sentinel lymph node biopsies should only be performed by experienced physicians who have first familiarized themselves with literature on the procedure, have established a protocol for all aspects of the procedure, and have successfully performed back-up axillary node dissections on a sufficient number of patients.
  • Surgeons who do not often perform breast cancer surgery should not perform sentinel lymph node biopsy.
  • If a �positive� (cancerous) sentinel lymph node is found, a full axillary node dissection should be performed.

The report of the steering committee of Health Canada's Canadian Breast Cancer Initiative was published in the July 24, 2001 issue of the Canadian Medical Association Journal. Click here to learn more about this report.

More recently, several studies have been published further suggesting that sentinel lymph node biopsy may be a promising advance in breast cancer surgery. In a small study published in 2003 in the The New England Journal of Medicine, researchers found that sentinel lymph node biopsy missed cancerous cells in only 9% of cases, and in most of these instances, the women did not develop a new cancerous tumor. Women who underwent sentinel lymph node biopsy also experienced less arm pain and better mobility compared to women who underwent standard axillary lymph node dissection.

In a June 2005 study published in the Journal of Clinical Oncology, British researchers found that women who underwent sentinel lymph node biopsy experienced significantly less arm swelling and numbness compared to women who under standard lymph node removal.

Are All Breast Cancer Patients Candidates for Sentinel Lymph Node Biopsy?

Not all women with operable breast cancer who have been recommended to have some of their axillary (armpit) lymph nodes removed are candidates for sentinel node biopsy. According to a steering committee of Health Canada's Canadian Breast Cancer Initiative, the following women are poor candidates for sentinel lymph node biopsy:

  • Women with palpable (able to be felt) lymph nodes
  • Women with locally advanced breast cancer
  • Women with multi-focal breast cancer (cancer in many areas of the breast)
  • Women who have previously undergone breast surgery (including breast reduction)
  • Women who have previously undergone radiation therapy to the breast

Moreover, the American Cancer Society states that sentinel lymph node biopsy is most suitable if there is a single tumor less than 5 centimeters across in the breast, no prior chemotherapy or hormone therapy has been given, and the lymph nodes do not feel enlarged.

Women should discuss the benefits and risks of sentinel lymph node biopsy with their cancer treatment team.

Additional Resources and References