A study to find sentinel nodes in rectal cancer (SentiRect)

Study design
This study was open to people having surgery for rectal cancer. Everyone had an injection of the tracer. 

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 taking part in the study had an MRI scan to see where the tracer had gone. This was done on the day it was injected or on the day of surgery.

Everyone then had the surgery that was already planned for them. 

There were 2 parts to this trial. 

Part A was for people having a type of surgery called a total mesorectal excision. 13 people joined this part.  

Part B was for people having a type of surgery called transanal endoscopic microsurgery (TEM). 2 people joined this part. 

For everyone taking part the doctor used a magnetic probe to locate the sentinel lymph node in the tissue around the rectum. This was during or after surgery, depending on the type of operation planned.

Results
The team had hoped to find 40 people to join. Recruitment was slow and only 15 people took part. The study closed earlier than planned but there were some findings to report. 

The study team looked at the:

• tracer dose
• way of giving it
• timings between the injection, MRI scans  and surgery

The team found that all of the above were acceptable. And that having the injection didn’t delay surgery. 

The team also looked to see if the technique was reliable enough to identify the sentinel node in the rectum. They found that it wasn’t reliable enough. 

Side effects
The team found that the tracer didn’t cause any side effects. 

Conclusion
The study team concluded the technique didn’t work well enough to help find the sentinel node in this small study. 

The team are keen that the technique isn’t rejected altogether. They think that more trials should be done to collect evidence about it. 

They suggest testing it in trials that use scans. This could help find out whether MRI scans to find lymph nodes in early rectal cancer could be improved. 

All trial results help doctors and researchers understand more about different cancers and the best way to treat them.

Where this information comes from
We have based this summary on information from the research team. As far as we are aware, the information they sent us has not been reviewed independently (peer reviewed )  or published in a medical journal yet. The figures we quote above were provided by the research team. We have not analysed the data ourselves.