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Tests and Procedures
Breast Health Centre: Sentinel Node

​What are sentinel nodes?

Sentinel nodes are the first nodes that cancer may spread to from a tumor as it would be the first node(s) that it would drain to.  Often 1 to 4 sentinel nodes may be sampled to give us a good indication of the nodal status of the remaining nodes.

Why not just remove all the nodes?

Over 80% of breast cancer patients have no node involvement.

If the sentinel nodes are free of cancerous cells, we can confidently assume the remaining nodes further away from the tumor are clear also. Therefore, we can prevent complete axillary node removal and all the complications that can arise from having them removed such as poor lymph drainage (lymphedema). If the sentinel nodes contain some malignant cells, you may then require further surgery to remove the remaining nodes. 

How is this procedure done?

On the day of your breast surgery, your surgeon would have made arrangements for you to go to one of the Nuclear Medicine departments (either at City Hospital or Royal University Hospital). If you were scheduled for a wire localization before your surgery, you would have that first, followed by the sentinel node imaging.

The procedure involves you having approximately four injections of a radiopharmaceutical around the nipple region of your breast. You will be lying down on a table with a gamma camera above it, with which images are taken shortly after the injections. These images identify the sentinel nodes and temporary markings may be made on your skin. Typically it takes about 30 - 60 minutes for this procedure, depending on the flow of the radiopharmaceutical and the size of breast. All the images will be reviewed by your surgeon before surgery. Once in the operating room, the surgeon uses a special probe to detect the exact location of the nodes by sensing the radioactivity.  Blue dye is then injected to make the nodes more easily identified during surgery.

Is the procedure painful?

The injections are somewhat uncomfortable as it is a needle prick just under the skin - you are not given any local anesthetic (freezing) as that would involve additional injections. The nipple region is a very sensitive region of the breast as it contains many nerve endings.  Fortunately, the injections are done quite quickly and within minutes the discomfort should ease.

Do I have to worry about radiation?

There is minimal amount of radioactivity from the dosage used. Therefore, you do not have to worry about damaging surrounding tissue or any other precautions for you or anyone else.  

Possible Temporary Side effects of Blue Dye

Most common side effect is green tinged urine for first 24-48 hrs post procedure as the kidneys excrete the blue dye -Less common, 1% of people (1 in 100 cases) may experience a temporary bluish tinge to the neck/face. This will fade with time.

How accurate is this procedure?

Using the radioactive dye along with the blue dye injected in the operating room, the success rate is close to 100%.

If my sentinel nodes are cancer free, does that mean I will require no further treatment?

There are two ways cancer cells can spread:

  • By the lymphatic system

  • By the vascular system

Therefore, even if your nodes are clear, your oncologist and surgeon may feel it best for you to receive some treatments as a precaution. This would depend on many factors such as the size and type of cancer as well as your age and general health. 

Last Modified: Wednesday, July 16, 2014 |
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