Surgeons at University of Washington Medical Center report encouraging results from an investigational mapping technique that uses minimal surgery to pinpoint the spread of breast cancer to the lymph nodes.
If there is suspicion that cancer may have spread via the lymph system, the current standard of care requires that most of the lymph nodes in the armpit be removed and biopsied for cancer. Whether or not cancer is found in the nodes, the result is the same: a large scar, considerable discomfort and shoulder stiffness, and sometimes permanent numbness, weakness and swelling of the arm.

"However, with lymphatic mapping, the spread of cancer can be tracked with much greater accuracy to the first or 'sentinel' node, reducing or eliminating the need for extensive surgery," said Dr. David Byrd, chief of surgical oncology and assistant professor of surgery.

Lymphatic mapping involves injecting two imaging substances next to the primary tumor site, before the tumor is removed surgically by lumpectomy or mastectomy.

First, a low-dose radioactive tracer is injected next to the tumor and a body scan follows the tracer's path through the lymph system to the lymph basin in the armpit on the same side as the breast cancer.

On the same day, a blue dye is injected next to the tumor. A few minutes later, an incision is made over the "hot spot" identified by the radioactive tracer. Looking for the blue-dyed node, the surgeon is able to visually determine the first or "sentinel" node in the drainage path from the tumor site. That node is removed and biopsied for cancer cells. If the sentinel node is cancer-free, experience at the UW and elsewhere in the country shows that in more than 90 percent of cases, the cancer has not spread to other lymph nodes.

While the current standard of care for metastatic breast cancer continues to mandate surgical removal of 10 to 25 lymph nodes under the arm once lymphatic mapping has been completed, "we hope this pilot program will demonstrate that in the near future, many patients will need to have only the sentinel node removed," said Byrd.

Byrd learned lymphatic mapping as a surgical fellow at the University of Texas M.D. Anderson Cancer Center in Houston, where the technique was pioneered as a means of determining the stage of cancer in patients with melanoma. In the past four and a half years, Byrd has performed lymphatic mapping in more than 200 patients with melanoma.

Byrd and colleagues began lymphatic mapping in patients with breast cancer in 1996 and have now performed the procedure in more than 30 patients.

With melanoma patients, technical advances in lymphatic mapping over the last few years have already resulted in the elimination of unnecessary lymph-node removal, when simple biopsy of the sentinel node shows that the tumor has not spread.