A guide to sentinel lymph node biopsy with the Magtrace® lymphatic tracer

Patient Guide

What to expect if you're having a sentinel lymph node biopsy with Magtrace® lymphatic tracer


Why have I been recommended for a sentinel lymph node biopsy (SLNB)?

When your surgeon removes your cancerous lump, it is also important for them to know whether the cancer has spread to other parts of the body, in order to determine the ‘stage’ of the disease.

The easiest way to establish this is by analysing your body’s lymph nodes. If cancer cells break off from their initial position, they will travel through the lymphatic channels that run to your underarm. Here, they will collect in the first lymph nodes they reach – known as the ‘sentinel’ lymph nodes.


What exactly is involved in a SLNB procedure?

A sentinel lymph node biopsy (SLNB), is a cancer staging procedure that takes place alongside the removal of a cancerous lump from your breast.

It involves identifying and then surgically removing a small selection of sentinel lymph nodes from your underarm, before analysing them to see if your cancer has spread beyond the initial lump.

How the Magtrace® lymphatic tracer is used

How will my surgeon find these sentinel lymph nodes?

To help identify the sentinel nodes, the Magtrace® lymphatic tracer will be injected into your breast. This magnetic ‘tracer’ liquid will follow the route that a migrating cancer cell would take, before collecting in the sentinel nodes in your underarm.

Once the tracer has migrated to your sentinel nodes, your surgeon will then be able to identify the location of these nodes by using a magnetic probe which can detect even minute quantities of the tracer signal. One benefit of Magtrace® is it guides your surgeon to remove only the nodes that could contain cancer cells, leaving any healthy nodes behind.

Once removed, these nodes will be sent to a pathologist who will analyse them to see if they contain cancer.

To learn more about the Magtrace® lymphatic tracer, please read our patient guide.

The procedure - what can I expect?

Injection before surgery

The Magtrace® lymphatic tracer will be injected at a time that suits you and your surgeon. It can be administered at the start of your surgery when you’re under anaesthesia, or many days or weeks beforehand, timed to coincide with your pre-surgical visit to the hospital or at a time that is convenient to you.

If done beforehand, local anaesthetic or a numbing gel will be applied. Your physician will then use a small needle to inject the liquid close to your nipple.

After the injection

Shortly after the injection, the Magtrace® lymphatic tracer liquid will flow through your lymphatic system, taking the route a migrating cancer cell would take, before collecting in the sentinel nodes in your underarm. Only the sentinel lymph nodes will be marked and will remain that way for many weeks.

In a small percentage of the 50,000 women who have been injected with Magtrace®, a small bruise-like mark on the skin can be seen, near to where it was injected.  This is just a tiny amount of the liquid that has remained under the skin, and the discolouration will fade over time.


During the procedure, your surgeon will use the Sentimag® probe to locate the Magtrace® lymphatic tracer in your sentinel lymph nodes. Once found, your surgeon will then remove two or three nodes on average for analysis.

Closer examination by a pathologist will reveal if any cancer cells are present in these lymph nodes and help determine if the cancer has began to spread to different parts of the body. This process can take some time, so if you do not hear back straight after surgery, do not worry.

What will the results from the analysis tell me?

This analysis will not only determine if cancer cells are present in your lymph nodes but how much cancer is in each one. This will help to accurately stage your cancer and help determine the best course of treatment, which may include additional therapy, such as chemotherapy and radiation.

Where can I find out more?

If you have any more questions about your surgery, please do ask your surgeon or the hospital team. We have a number of resources around our website about the Magtrace® lymphatic tracer, which you are welcome to read.

We hope that the information above has helped you understand a little more about what’s involved in having cancer staged with the help of Magtrace®.