Canadian Report Outlines Benefits and Challenges of Sentinel Lymph Node Biopsy (dateline August 1, 2001)
Surgeons often remove some or all of the axillary (armpit) lymph nodes in women with breast cancer to "stage" the cancer and determine the most appropriate treatment options.The standard surgery for removing these lymph nodes is called axillary node dissection. However, a relatively new procedure called sentinel lymph node biopsy, is becoming more common.
Instead of removing 10 to 20 lymph nodes or more with axillary node dissection, sentinel lymph node biopsy involves removing only one to three lymph nodes. While sentinel lymph node biopsy has been associated with reduced side effects, the procedure is new, and long-term data on its safety and effectiveness are still being gathered. Recently, a steering committee of Health Canadas Canadian Breast Cancer Initiative conducted a systematic review of English-language literature on sentinel lymph node biopsy from 1991 to 2000. Based on their review, the committee has made a number of recommendations for physicians and patients regarding the use of sentinel lymph node biopsy in women with breast cancer.
A few of the committees key recommendations/explanations are described below:
Axillary node dissection is the standard of care for staging operable breast cancer.
The removal of several axillary (armpit) lymph nodes with axillary node dissection is still the standard of care for breast cancer that can be treated with surgery. Determining whether the axillary lymph nodes contain cancer is very important in accurately establishing the extent (stage) of the cancer, determining the patients prognosis, and achieving local control of the cancer, according to Dr. Mark Levine of McMaster University and his fellow committee members. In particular, achieving local control of the cancer can increase long-term survival. However, the committee admits that axillary node dissection can sometimes be associated with side effects, such as wound infection, restriction of shoulder movement, arm problems (stiffness, loss of sensation), pain, and lymphedema (chronic arm swelling).
Sentinel lymph node biopsy is a new procedure that involves removing far fewer lymph nodes. With this procedure, the surgeon removes the first one to three "sentinel" lymph nodes, the first nodes in the lymphatic chain, to determine whether they contain cancer. If the sentinel nodes are cancer-free, there is usually no need to remove the remaining lymph nodes because they are most likely cancer-free as well. However, if the sentinel nodes do contain cancer, a full axillary node dissection is necessary.
Patients should be aware of the benefits and challenges of sentinel lymph node biopsy.
The committee described a number of potential benefits of sentinel lymph node biopsy. A major benefit is that the procedure is associated with significantly fewer side effects. For instance, lymphedema, the chronic swelling of the arm, can affect approximately 15% to 20% of breast cancer patients who undergo axillary node dissection. With sentinel lymph node biopsy, fewer lymph nodes are removed, reducing the chances of lymphedema. The incidence of other side effects may also be reduced.
However, a main challenge of sentinel lymph node biopsy is that the procedure itself is difficult to master. Failure to correctly identify the sentinel node(s) and false positive results (mistakenly reporting that cancer is present) are two potential problems with the surgery. The committee cited research to support that performing several sentinel lymph node biopsies greatly increases a surgeons accuracy at correctly identifying the sentinel lymph node(s) and reduces false positive results. The committee also noted that long-term data on the rate of breast cancer recurrence and overall survival with sentinel lymph node biopsy are not yet available because the procedure is so new.
The committee 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; 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 patients treatment after surgery and the chances that breast cancer may return.
Physician experience improves accuracy of sentinel lymph node biopsy.
To address some of the challenges of sentinel lymph node biopsy, the committee recommended guidelines for both physicians and patients. First, physicians should familiarize themselves with the literature on sentinel lymph node biopsy and follow an established protocol for all aspects of the procedure (nuclear medicine, surgery, pathology). The committee also recommended that physicians perform "back-up" axillary lymph node dissections on patients after the sentinel lymph node biopsy until an acceptable success rate is reached.
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. Because physician experience is so important, the committee also recommended that sentinel lymph node biopsy not be performed by physicians who do not perform breast surgery often.
Concerning patients, the committee recommended that patients ask their surgeons how many sentinel lymph node biopsies they have performed and the surgeons success rate with the procedure. Patients and physicians should also be aware that not all women are candidates for sentinel lymph node biopsy. Poor candidates for the procedure include those with palpable lymph nodes (nodes large enough to be felt, suggesting that they may be cancerous), locally advanced breast cancer, multi-focal breast cancer (cancer in many areas of the breast), and those who have previously undergo breast surgery (including breast reduction) or radiation to the breast.
- 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.
- Sentinel lymph node biopsy should not be performed on women with palpable (able to be felt) lymph nodes, locally advanced breast cancer, multi-focal breast cancer (cancer is in several areas of the breast), or those who have previously undergone breast surgery or radiation to the breast.
The full report by the steering committee of Health Canadas Canadian Breast Cancer Initiative was published in the July 24, 2001 issue of the Canadian Medical Association Journal (see reference below).
Additional Resources and References
- The report, "Clinical Practice Guidelines for the Care and Treatment of Breast Cancer: 13. Sentinel Lymph Node Biopsy," is published in the July 24, 2001 issue of the Canadian Medical Association Journal. A patient version of the guidelines appears in Appendix 1. To access the report and/or patient version, please visit http://www.cma.ca/cmaj/
- To learn more about sentinel lymph node biopsy, please visit http://www.imaginis.com/breasthealth/sentinelnode.asp
- To learn more about axillary node dissection, please visit http://www.imaginis.com/breasthealth/mastectomy.asp#axillary
- To learn more about lymph nodes and the lymphatic system, please visit http://www.imaginis.com/breasthealth/lymph_nodes.asp