When treating breast cancer, one of the most important considerations is whether the tumor has spread beyond the breast. Evaluation of the axillary lymph nodes remains an important method in determining the answer to this question. Physical exam, x-rays, and blood tests are not sufficiently accurate to determine whether tumor has spread. Therefore several of the lymph nodes are removed and examined under a microscope by the pathologist. The surgical procedure to remove these lymph nodes is called an axillary dissection and is done whether the patient chooses breast conservation or a mastectomy. The operation involves removing a mass of fatty tissue under the arm that contain the lymph nodes. Then the pathologist picks through the tissue and finds a variable number of lymph nodes (5-20).
This procedure has evolved over the years to result in removing enough lymph nodes to accurately stage the cancer and not so many to cause problems. Extensive removal of the axillary lymph nodes can result in swelling of the arm which is painful, disfiguring, and increased the vulnerability of the arm and hand to infection. The standard lymph node dissection currently done causes lymphedema in 5-10% of patients and when it occurs it is nearly always controllable with physical therapy and massage techniques. Truly disabling lymphedema is very unusual.
Surgeons are now using a technique called sentinel lymph node biopsy that identifies the lymph node(s) most likely to contain the cancer cells if they have spread beyond the breast. A combination of radioactive tracer and blue dye are injected around the tumor and then flow into the first draining lymph node. This can be identified and removed. The sentinel node technique is best suited to patients that have small tumors because only 5 to 15 percent of them have tumor in their lymph nodes. One disadvantage of the procedure is that if tumor is found in any of the sentinel lymph nodes the patient will need to return to the operating room on another day and have the standard axillary dissection. Patients with larger tumors should consider having the standard axillary dissection done at the time of the initial operation.
On the day of your operation you will have a small amount (4 cc, which is approximately 1/8 ounce) of radioactive technetium sulfur colloid injected into the breast in the tissue under the nipple. This can be done in the hospital or in the doctor’s office. The injection will be done with a needle smaller than those used to draw blood. You will then be taken to the operating room and undergo general anesthesia. After you are asleep the isosulfan blue dye may be injected into the breast in the tissue under the nipple or around the tumor. The surgery will then proceed and the lymph nodes containing increased radioactivity and/or blue dye will be identified using a sensitive Geiger counter and seeing blue dye in the tissue.
The radioactive material to be injected is called Technetium-labeled sulfur colloid (Tc99). Technetium sulfur colloid is fully approved for use in humans. It is widely used for liver/spleen scans and other diagnostic tests. It is not a new or experimental drug. The dose of radioactivity you will receive from the injection is less than what you get in a single chest x-ray. When Technetium sulfur colloid is used for bone scans, the dose is 20 times what is used in this study. There is no danger to others around you from the small amount of radioactivity. Any radioactivity not removed in the tissue with surgery will disappear over 1-2 days. No precautions are needed and no one around you will receive any radiation dose. The blue dye is isosulfan blue. Isosulfan blue is fully approved for use in humans, and is also used in the detection of lymph nodes in melanoma (a kind of skin cancer). Allergic reactions to Technetium sulfur colloid and isosulfan blue dye are exceedingly rare and consist of a rash or some bronchoconstriction. Most of the blue dye will be removed with the surgery. Some of the blue dye may be excreted in the urine turning it a light blue or green color. Any remaining blue color in the skin or breast will disappear over a few weeks.
The sentinel node biopsy procedure will allow us to gain the same information and remove fewer lymph nodes. This reduces the discomfort, risk of lymphedema , and numbness in the armpit. The drain tube is usually removed more quickly. There is a 1 - 3 percent risk of a false negative test. This means that the sentinel nodes did not have any tumor in them but there is actually tumor in some of the other nodes. This is approximately the same risk of obtaining a false negative result with the standard axillary dissection. The major drawback to the procedure is that if the pathologist determines that there is tumor in the sentinel node(s) when the studies are completed 2 - 3 days after the operation, then you may need to return to the OR for a complete axillary dissection.