To help doctors give their patients the best possible care, the American Society of Clinical Oncology (ASCO) asks its medical experts to develop evidence-based recommendations for the use of sentinel lymph node biopsy for early-stage breast cancer. This guide for patients is based on ASCO's recommendations.
- A sentinel lymph node biopsy is a procedure that helps the doctor know whether breast cancer has spread to the lymph nodes.
- An axillary lymph node dissection may also be needed to understand how the cancer has spread.
- Talk with your doctor about what kind of procedure is recommended to diagnose cancer and what the results will mean.
Lymph nodes are tiny, bean-shaped organs that fight infection and disease and filter cancer cells. A sentinel lymph node biopsy (often shortened to sentinel node biopsy, or SNB) is a procedure where one or a few lymph nodes are removed from under the arm and examined for evidence of cancer. When cancer spreads from the breast, it travels through the lymphatic system. The first lymph node or group of lymph nodes encountered is called the sentinel node. In most patients, if no evidence of cancer is found in the sentinel node, it can be expected that no cancer will be found in the remaining axillary (underarm) lymph nodes. Knowing whether the cancer has spread helps determine the stage and approach to treatment. That is, cancer that has spread to the lymph nodes may be treated differently than cancer that has not spread to the lymph nodes.
To locate the sentinel node, the surgeon injects a harmless, radioactive substance and/or a blue dye into the breast near the tumor. Then, the surgeon makes an incision under the arm and either follows the radioactive signal or finds the lymph nodes that are stained blue and removes them. Usually, between one and three nodes are removed. A pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease) then carefully examines the sentinel node(s) for evidence of cancer.
Axillary Lymph Node Dissection
Another way of evaluating lymph nodes is with an axillary lymph node dissection. During this procedure, most lymph nodes under the arm (generally 20 to 25) are removed and examined for evidence of cancer. Because more lymph nodes are studied, the doctor may have more evidence of whether the cancer has spread. However, this procedure can result in long-term complications or disabilities, including pain and numbness in the arm and lymphedema  (excess fluid in the arm that causes swelling). Although some patients may experience side effects from SNB, these are usually milder than the side effects experienced after an axillary lymph node dissection.
ASCO recommends the following for the use of SNB:
- SNB can be used instead of axillary lymph node dissection for many patients with early-stage breast cancer and no clinically suspicious lymph nodes (usually meaning that the doctor cannot feel them during an examination).
- If the results of the SNB show no evidence of cancer, and an experienced surgeon has done the procedure, an axillary lymph node dissection is not needed. Experience generally means that a surgeon has performed this procedure many times with correct results.
- If the results of the SNB show evidence that the cancer has spread, then axillary lymph node dissection is recommended.
What This Means for Patients
For many patients with smaller tumors, SNB is an appropriate procedure to determine whether cancer has spread outside of the breast and can be performed instead of an axillary lymph node dissection. SNB is associated with fewer long-term side effects than axillary lymph node dissection. However, it is not yet known whether SNB affects long-term survival in patients with breast cancer.
However, patients with larger tumors or clinically suspicious lymph nodes should have an axillary lymph node dissection instead of SNB. In addition, if the results of the SNB are positive for cancer, then a complete axillary lymph node dissection is needed to determine how far the cancer has spread. Talk with your doctor about whether SNB is an option for you.
If the results of the SNB show that the cancer has not spread, an axillary lymph node dissection is not needed, as long as an experienced surgical team performed the procedure.
Questions to Ask the Doctor
Consider asking your doctor the following questions:
- Do you recommend that I have a SNB? Why or why not?
- Do you recommend an axillary lymph node dissection instead? Why or why not?
- What are the risks of the procedure you recommend?
- If I need an axillary node dissection, what can I do to prevent or minimize the risk of lymphedema?
- Can you recommend an experienced surgeon to perform this procedure?
- When will I know the results? How will they be communicated to me?
- What further tests will be necessary if the results are positive (indicates cancer)? What if they are negative? What follow-up care will I need after the procedure?
- Will I have a surgical drain after surgery?
- What can I expect in terms of range of motion in my arm?
- Will I need to do daily exercises after surgery?
- Where can I find more information?
Read the entire clinical practice guideline at www.asco.org/guidelines/breastsnb .
About ASCO's Guidelines
To help doctors give their patients the best possible care, ASCO asks its medical experts to develop evidence-based recommendations for specific areas of cancer care, called clinical practice guidelines. Due to the rapid flow of scientific information in oncology, new evidence may have emerged since the time a guideline or assessment was submitted for publication. As a result, guidelines and guideline summaries, like this one, may not reflect the most recent evidence. Because the treatment options for every patient are different, guidelines are voluntary and are not meant to replace your physician's independent judgment. The decisions you and your doctor make will be based on your individual circumstances. These recommendations may not apply in the context of clinical trials.
The information in this guide is not intended as medical or legal advice, or as a substitute for consultation with a physician or other licensed health care provider. Patients with health care-related questions should call or see their physician or other health care provider promptly, and should not disregard professional medical advice, or delay seeking it, because of information encountered in this guide. The mention of any product, service, or treatment in this guide should not be construed as an ASCO endorsement. ASCO is not responsible for any injury or damage to persons or property arising out of or related to any use of this patient guide, or to any errors or omissions.
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