A diagram of the lymphatic system in a woman's underarm area is available for downloading and publication at http://www.unc.edu/news/newsserv/pics/lymphnod.jpg
By LESLIE H. LANG UNC-CH School of Medicine
CHAPEL HILL, N.C. - A multi-center study published in The New England Journal of Medicine last October showed that sentinel lymph node biopsy - the removal of some of the first lymph nodes into which cancerous cells from the breast might drain - is as effective for determining the spread of disease as totally removing all the lymph nodes under the arm.
That journal report and subsequent media coverage helped trigger an ongoing demand for sentinel lymph node biopsy among women diagnosed with invasive breast cancer.
These patients are candidates for either breast-preserving therapy or mastectomy. They see in sentinel node biopsy an alternative to complete axillary (armpit) lymph node resection, or lymphadenectomy. This major operation requires general anesthesia with its attendant risks. It also often results in persistent numbness and tingling in the armpit and, in some patients, causes swelling of the arm to twice its size, requiring special care for life.
The demand for the new biopsy also has prompted a surge in requests from community-based surgeons for lessons in the technique, says Dr. David Ollila, assistant professor of surgery at the University of North Carolina at Chapel Hill School of Medicine and a member of the UNC Lineberger Comprehensive Cancer Center.
"Use and demand for this technique is truly exploding across the country, yet the whole field is very young," he says. "The first description of the technique in breast cancer patients was less than five years ago."
Ollila and his UNC-CH colleagues in surgical oncology note that sentinel lymph node biopsy is technically challenging to perform and that its success rate could vary widely among surgeons and institutions. They urge breast cancer patients seeking to avoid complete axillary resection to first ask about the "false negative rate" of their surgeon and medical institution.
"Doing so could reduce one's risk of being told that the biopsy results were negative -- that the cancer has not spread beyond the breast - when, in fact, it actually has," Ollila says. "The false negative rate, according to studies, could range from 0-11 percent, which could mean one or more in 10 women will not get their disease properly staged, nor will they get the proper chemotherapy regimen up front."
"Specifically, I think it's imperative that a woman ask her surgeon how many of these biopsies have you done and what is your false negative rate?" Ollila adds. "I've done more than 125 procedures over the last three years, both on the West Coast and here at UNC. I think the literature supports that surgeons should perform at least 20-25 sentinel node procedures, followed by complete axillary resection, to ensure that they are accurately identifying the sentinel node."
In a clinical "validation trial" at UNC-CH, patients with invasive breast cancer undergo the sentinel node procedure followed by complete lymphadenectomy.
"We're validating that our team of nuclear medicine physicians, surgeons and pathologists working in concert can successfully identify the sentinel node. If you correctly identify the patient's sentinel node and the pathology studies show that it's tumor-free, then there is no reason to take the remaining axillary lymph nodes. Thus, the patient can be spared a formal axillary resection," Ollila says.
After studying 65 consecutive patients, the UNC-CH team is 100 percent accurate in identifying the sentinel node with no false negative diagnoses.
According to Ollila, three factors account for these study results. "We have people who are very knowledgeable in the use of sentinel node biopsy for melanoma, its first clinical application. We were able to transition to the breast by proceeding very meticulously in concert with our colleagues in nuclear medicine and pathology. And I think we understood the pitfalls and how to avoid them."
At UNC-CH, sentinel lymph node biopsy candidates receive an injection of radioactive tracer material around the primary tumor. In the operating room, blue dye is injected into the same area. "So in the operating room, we have two methods available to look for the sentinel node. We can visually identify the lymphatic path going directly to the first draining node, and we can use a hand-held gamma probe to trace the radioactivity as it travels through the lymphatics to the sentinel node," Ollila explains.
The node is carefully removed with minimal trauma to surrounding tissue and then sent to the pathology laboratory for further scrutiny.
"We have demonstrated with a high degree of certainty that we can successfully identify the sentinel node," Ollila says. "I think we're ready as a group to say we are done with the validation trial and can offer a sentinel node-only procedure for women with invasive breast cancer."
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