Fluid from the breast drains through lymphatic vessels to lymph nodes located in the armpit. A sentinel lymph node is the first lymph node to receive lymphatic drainage from a tumor. In most cases, this node is the first node involved by cancer if the cancer spreads to the armpit lymph nodes. The sentinel lymph node can be detected by injection of a blue dye and a radioactive tracer near the primary tumor.
The dye, isosulfan blue, is injected at the time of the surgery in and around the area of the breast tumor, and within a few minutes passes through the lymph channels to the lymph nodes in the armpit.
Two hours prior to the surgery, the tumor is also injected with an extremely small dose of technetium sulfur colloid. This is a nuclear tracer which will also pass to the axillary lymph nodes. During the sentinel node biopsy, the blue dye is visualized to help identify the sentinel node and a special Geiger counter device is used to identify the node or nodes that takes up the nuclear tracer. Frequently, more than one sentinel lymph node is removed at surgery. A frozen section or touch preparation rapid evaluation of the sentinel lymph node is performed by a pathologist at the time of surgery. If this test reveals cancer cells in the lymph node, additional lymph nodes (levels I & II) will be removed from the armpit. This is called an axillary dissection. An axillary dissection can cause swelling of the arm (lymphedema), persistent discomfort in the armpit, and areas of numbness in the upper arm. With early detection of breast cancer, the axillary lymph nodes will be normal 80% of the time.
After surgery, multiple special tests are performed on the sentinel node to determine if there may be any microinvasion with cancer into this node. Up until now, this testing was impractical because the sentinel node could not be identified successfully previously. This technique successfully identifies the sentinel node over 95% of the time.
The isosulfan blue dye is a very safe dye. It may result in temporary staining of the patient’s skin, giving it a different hue for several hours after the operation. Slight discoloration of the breast skin may persist permanently. It may give urine a greenish color for a day after the operation. Very rarely, there can be allergic reactions to the dye. The nuclear tracer, technetium sulfur colloid, is also extremely safe. It is given in a very small dosage and no special precautions have to be taken by those involved in handling the tissue at the operation.
We feel that this technique is a major advancement in breast cancer surgery and significantly benefits the care of the breast cancer patient.