Sentinel Lymph Node mapping in Melanoma and Breast Cancer


 

Like many cancers, malignant melanoma and invasive breast cancer often spread from their original site through the lymph channels to regional lymph nodes. With melanoma, removal of these lymph nodes can prolong life and in some cases cure the disease; in breast cancer removal of these lymph nodes provides prognostic information regarding cure and can help decide whether there is a need for chemotherapy.

There clearly appears to be a role for the removal of regional lymph nodes in melanoma and invasive breast cancer. Unfortunately, this operation is often leads to a significant number of temporary and permanent complications including arm and leg swelling, poorly healing incisions and a loss of skin sensation. When the regional lymph nodes are removed in intermediate depth melanoma less than 15 percent of patients have proven metastasis(i.e., cancer in the lymph nodes), while less than 20 percent of patients with early breast cancer have proven metastasis. The routine use of lymph node removal in these two cancers unnecessarily exposes all these patients to the complications of the procedure while providing benefit to only those with metastatic disease.

Sentinel lymph node mapping is a new way to evaluate regional lymph nodes. It is currently in routine use for the treatment of malignant melanoma and is under study for its role in breast cancer. This minimal surgical procedure spares 80 percent of patients the greater surgical procedure of regional lymph node dissection by identifying those patients that will benefit from the more extensive removal of lymph nodes. This approach allows the surgeon to identify and biopsy the first or "sentinel" lymph node which the cancer encounters as it spreads to the regional lymph nodes. If the sentinel lymph node is free of cancer, studies show that all lymph nodes in that region are free of cancer and complete lymph node removal is unnecessary.

Two hours before the operation the radiologist injects a nuclear isotope around the melanoma or breast cancer and 45 minutes later obtains a nuclear scan to determine the "hot" sentinel lymph nodes to which the isotope has spread. Fifteen minutes before the operation begins, the surgeon injects a blue vegetable dye around the tumor site which also helps identify the lymph nodes. In the operating room, the melanoma or breast cancer is excised first and then the sentinel lymph node is identified. Using a hand-held Geiger counter, the surgeon pinpoints the sentinel lymph nodes beneath the skin and makes a small incision over them. Using the Geiger counter and visualizing the blue dye which has spread to the sentinel lymph nodes, the surgeon can isolate and remove these with minimal dissection. This completes the surgery and only if subsequent studies demonstrate metastatic tumor in the sentinel lymph nodes will complete lymph node removal be recommended Preoperative lymph node mapping and lymph node biopsy (removal) and combined with wide excision of the local melanoma or breast cancer will often be the only surgical procedure required.

At the present time we are able to offer this procedure at Torrance Memorial Medical Center and at Little Company of Mary Hospital. While some surgeons use the isotope or blue dye alone, we believe the two in combination offer the greatest accuracy. We agree with most national experts that sentinel lymph node mapping is the standard of care for intermediate thickness melanomas while its role in breast cancer is still under investigation.