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A recent study of surgeons from 42 institutions finds that the sentinel lymph node biopsy procedure is effective at determining whether breast cancer has spread to the lymph nodes. Whether the nearby lymph nodes contain breast cancer is an important indicator when assessing the extent of the cancer. Sentinel lymph node biopsy is a relatively new procedure that involves removing only one to three lymph nodes to determine whether the cancer has spread. Initial studies have shown that sentinel lymph node biopsy may be associated with less pain and fewer complications than the standard lymph node removal procedure. Now, this latest analysis shows that the procedure is also accurate, which means it is likely to become more common at community and regional hospitals. When breast cancer cells begin to escape from the primary tumor site in the breast, they travel to the lymph nodes under the arm. Therefore, physicians usually remove some or all of the axillary (armpit) lymph nodes during breast cancer surgery and have them analyzed for traces of cancer cells. The standard method of removing lymph nodes, axillary lymph node dissection, involves removing 10 to 30 lymph nodes. Though the standard procedure is highly accurate at detecting cancer cells, it can also cause lymphedema—chronic arm swelling—in approximately 10% to 20% of women. Sentinel lymph node biopsy involves using a low-level radioactive substance and a dye to identify the first lymph nodes (the "sentinel" node or nodes) in the lymphatic chain so that these are the only lymph nodes removed. Pathologists determine whether the lymph nodes have been affected by the breast cancer based on whether these sentinel nodes contain cancer cells. 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. (Additional lymph nodes must be removed if the sentinel lymph node analysis reveals cancer cells). While sentinel lymph node biopsy has been performed by some surgeons for years, experts cautioned that more clinical trial results were needed before the procedure became a widespread replacement for standard axillary lymph node dissection. To investigate the effectiveness of sentinel lymph node biopsy, Steve Shivers, PhD, and his colleagues from the Moffitt Cancer Center and Research Institute in Tampa, Florida conducted the "Department of Defense Multicenter Breast Lymphatic Mapping Trial." The trial involved 111 surgeons from 42 institutions, including 12 university-based research centers. The surgeons first completed a two-day training course at the Moffitt Cancer Center and then returned to their respective institutions to perform the procedure on 965 breast cancer patients. The first 20 to 25 of each surgeon’s sentinel lymph node biopsies were followed by axillary lymph node dissections to determine whether they accurately identified the sentinel nodes. After acquiring experience with the procedure, the surgeons performed only sentinel lymph node biopsies. Dr. Shivers and his colleagues found that at community and regional hospitals, surgeons were able to identify the sentinel lymph node in 85% of the cases. Furthermore, only 4% of cases produced false-negative results; that is, the patient’s lymph nodes contained cancer despite a cancer-free sentinel node. Patients were followed for an average of 16 months after the procedure and will continue to be followed. Based on these successful results, the researchers say it is reasonable to suggest that sentinel lymph node biopsy can be accurately performed in community and regional hospitals, as well as in major university-based centers. Because the procedure requires experience to accurately identify the sentinel lymph node, the American College of Surgeons Oncology Group recommends that physicians perform at least 30 sentinel lymph node biopsies followed by complete axillary lymph node dissection, with an 85% success rate in identifying the sentinel lymph node(s) and a 5% or lower false positive rate, before performing the procedure without a back-up axillary node dissection.
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