Sentinel Lymph Node Biopsy
Sentinel Lymph Node Biopsy, also known as selective lymphadenectomy and intraoperative lymphatic mapping, is a relatively new procedure for patients diagnosed with melanoma and with breast cancer. The procedure was initially studied in patients with melanoma to determine if they should have an elective lymph node dissection at the time of the diagnosis of melanoma or if it would be safe to observe the nodal areas without an operation. The sentinel node is the first draining node of a regional lymph node basin. For example, if a melanoma were on the arm, the regional nodes of importance are usually in the axilla (under the arm). For patients with breast cancer, the sentinel node most commonly is also in the axilla.
In theory, the sentinel node is the first node cancer cells would lodge if they were to travel through the lymphatics. By removing and testing this sentinel node for cancer cells, it can be determined whether or not more extensive surgery is required. The studies had been very encouraging for both patients with breast cancer and melanoma. This procedure is usually done at the time of the definitive surgery to remove the melanoma or the breast cancer.
For patients with melanoma, the procedure is performed by injecting the site of the melanoma with a radioactive material called technetium. For patients with breast cancer, the injection is done at the site of the cancer. Technetium is also used for bone scans, a common test for many cancer patients. After the injection, the lymph node draining areas are scanned to find the hot spot that indicates the sentinel node. The nuclear medicine doctor then marks the spot with an "X" on the skin. The patient next goes to the operating room where the area is scanned with a hand held probe that detects signals from the node to more closely pinpoint the exact location of the sentinel node. The site of the melanoma is also injected with a blue dye that travels through the lymphatics and stains the sentinel node blue. The surgeon then makes a small incision over the site where the sentinel node is located, uses the probe to help locate the node by identifying an increase in signal and also looks for the blue dye. Once removed, the node is sent to the pathologist, who will perform routine and special tests to determine if there is any evidence of cancer cells. If the node is "negative", meaning no cancer cells were detected, no further surgery is required in the lymph node area. If the node is "positive", meaning cancer cells were detected, further surgery is required to remove the rest of the nodes in that specific nodal region.
The purpose of this technique is to identify patients who would require a less extensive operation and continue to receive the best treatment and care available. The goal of this procedure has been met successfully.
