A study of a new way to find sentinel nodes in rectal cancer (SentiRect)

Please note - this trial is no longer recruiting patients. We hope to add results when they are available.

Cancer type:

Bowel (colorectal) cancer
Rectal cancer





This study is looking at using magnetic tracers to help find the first lymph nodes that rectal cancer might have spread to.

The first lymph node that cancer cells in lymphatic fluid reach is known as the sentinel node. If cancer of the rectum (back passage) has spread to the lymph nodes, the sentinel lymph node is likely to contain cancer cells.

More about this trial

The usual treatment for rectal cancer is surgery. For some people, there is a risk that the cancer has spread elsewhere in the body through the lymphatic system. So you usually have scans before surgery to check for this. But sometimes these scans are not completely accurate at finding cancer in the lymph nodes.

Finding and checking the sentinel node may help doctors work out which type of operation is most suitable. If the sentinel node is free of cancer cells, there may be very little risk that there are cancer cells in any of the other nodes. This could mean you have a smaller operation, preserving the rectum. But there isn’t yet an effective way to find the sentinel nodes in the rectum.

In this study, researchers are testing a new technique to find the sentinel node. It uses a magnetic tracer and detector to find the sentinel node.

The study is in 2 parts. Part A is to see how accurate the technique is at finding the sentinel node. Part B is to find the node and then see if it is possible to remove it.

The researchers hope to test the technique in a large group of people, but first they need to run a small pilot (feasibility) study to see if people would find the techniques acceptable.

The aims of the study are to:

  • find out how accurate the tracer and detector are at finding the sentinel node and then if it is possible to remove it
  • learn more about the side effects of having the tracer
  • find out if having the tracer makes surgery more difficult

Who can enter

The following bullet points list the entry conditions for this study. Talk to your doctor or the study team if you are unsure about any of these. They will be able to advise you.

You might be able to join this study if all of the following apply. You

  • Are able to have surgery for rectal cancer
  • Are due to have your case discussed by the colorectal multi disciplinary team (MDT) at Oxford University Hospitals NHS Trust
  • Are aged between 18 and 90

You cannot join this study if any of these apply. You

  • Are sensitive to iron or dextran compounds, magnetic tracers or any substance the tracer contains
  • Have cancer in the muscles around the anus (anal sphincter)
  • Are pregnant or breastfeeding

To join part B, the following must also apply.

  • You can take part if you have early rectal cancer and your MRI scan showed you don’t have cancer in the lymph nodes
  • You cannot take part if you have advanced cancer or your MRI scan showed you have cancer in the lymph nodes

Trial design

This study is based in Oxford. The study is in 2 parts. The researchers need 40 people to join in total. Part A is to see how accurate the technique is at finding the sentinel node. Part B is to find the node and then see if it is possible to remove it.

You have a flexible sigmoidoscopy or colonoscopy a week before surgery. This is standard and helps the surgeon assess your cancer.

During your procedure, the doctor injects the tracer around the tumour. You won’t be able to feel this.

The tracer consists of tiny nanoparticles of iron which can be magnetised. When these particles get into the body’s tissue, they are filtered out and removed from the system by the lymph nodes. The particles are so small they then stay trapped in the lymph node.

A handheld probe called Sentimag generates a small magnetic field. This magnetises the iron nanoparticles so the probe can then locate the sentinel lymph node. 

Everyone has an MRI scan to see where the tracer has gone, on the day it is injected or on the day of surgery.

A week later, you have the surgery that was already planned for you.

Part A
You can join part A if you are having surgery to remove rectal cancer and surrounding tissues that contain lymph nodes. After the operation, a doctor called a pathologist will examine the removed tumour. This usually happens after cancer surgery. But in this study, they will also use the hand held probe that detects the tracer to find the sentinel node.

Part B
You can join part B if you are having a type of surgery called transanal endoscopic microsurgery (TEM). You have this surgery for early rectal cancer.

During the operation, the surgeon uses the probe to find the lymph node. The surgeon will remove the sentinel lymph node if possible, along with the tumour. It will be sent to the pathologist who will examine it as usual. 

Hospital visits

You don’t have any extra hospital visits if you join this study

The study team can tell you more about how long you stay in hospital after surgery. This depends on the type of surgery you are having 

Side effects

There is a very small chance of an allergic reaction to the injection (tracer), which may cause:

  • rash
  • itching
  • dizziness
  • light headedness
  • very rarely, a severe allergic reaction

These symptoms generally settle down without any treatment, but you will be given a phone number to call in case you do develop any of these symptoms after leaving the hospital.

Finding the sentinel node during surgery could mean the operation takes a bit longer. This might slightly increase the risk of complications after surgery such as bleeding.

The study doctors will explain all the possible side effects before you join the study.

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Mr Chris Cunningham

Supported by

Colorectal Therapies Healthcare Technologies Cooperative
Oxford University Hospitals NHS Trust
University of Leeds

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Around 1 in 5 people take part in clinical trials

3 phases of trials

Around 1 in 5 people diagnosed with cancer in the UK take part in a clinical trial.

Last reviewed:

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