Dear OncoLink "Ask The Experts,"
My mom is having a sentinel lymph node biopsy. Can you tell me what she should expect from this test?
The lymph system is part of your body's defense against infection. It is made up of lymph vessels and lymph nodes. The lymph vessels collect fluid and protein from surrounding body tissues and lymph nodes act as a filter that traps bacteria, viruses or even cancer cells. Because of this, lymph nodes in the armpit (axilla) are routinely checked as a standard part of breast cancer surgery for women who have invasive breast cancer. If breast cancer is non-invasive (in-situ ) then the lymph nodes are not routinely checked, though there are circumstances in which it would be recommended.
The lymph nodes clustered under the arm drain fluid from both the breast and arm. Surgeons are interested in figuring out which lymph nodes, out of all the lymph nodes in the axilla, are the ones that first drain the breast. This procedure is called a Sentinel Lymph Node Mapping and Biopsy. On average, most women have 1-2 sentinel lymph nodes, though sometimes there are more. There are approximately 15-25 lymph nodes total under the arm, though again we are all different and some women may have more or less than that. A full axillary lymph node dissection removes most of these lymph nodes.
In the sentinel lymph node procedure, either one or two types of dyes are typically used to map out the correct lymph nodes. These include a blue dye and a radioisotope. The radioisotope is usually injected in nuclear medicine, while you are awake. It is usual for them to numb the breast first before giving the injection. The blue dye is given in the operating room, after you are already asleep. During the operation, the surgeon can see which nodes have the blue dye and they use a hand held scanning device to identify which nodes have the radioisotope. Those lymph nodes are removed (again, the average is 1-2 lymph nodes). It is important to remember that just because the dye went to these lymph nodes does not mean they have cancer in them. It just means they are the right lymph nodes to check for cancer.
The sentinel lymph node procedure is a same day surgery, meaning you come in and go home the same day. Most women feel a bit more discomfort from this surgery than the breast surgery. It still doesn't keep you from being up and about, but it's good to know that it can be more uncomfortable. As the area heals, it is not uncommon to feel shooting burning sensations. This is normal and will go away. The blue dye that is used, gets out of your body through your bowel and kidney, so don't be surprised if your urine and stool are a blue-green color for a few days. Sometimes the dye also stains the breast – which will eventually go away.
The length of time for the results of the sentinel lymph node biopsy varies between hospitals. Some will do a frozen section the day of surgery, and others will wait for a final pathology report which can take a few days to 7-10 days. You will need to talk to your surgical team about this. If cancer is found in a sentinel lymph node, it is usually recommended that you go back on another day for a completion axillary lymph node dissection.