Intended for healthcare professionals


Breast cancer: NICE recommends innovative magnetic technology for locating sentinel lymph nodes

BMJ 2022; 377 doi: (Published 17 May 2022) Cite this as: BMJ 2022;377:o1226
  1. Jacqui Wise
  1. Kent

A magnetic liquid tracer and a handheld sensing probe are now recommended as an option to help surgeons establish whether breast cancer has spread.

Hospitals with limited or no access to a radiopharmacy department could particularly benefit from the Magtrace and Sentimag system, said draft guidance from the National Institute for Health and Care Excellence (NICE).1 The new technology could also reduce the reliance on having radioactive isotopes shipped into the country, meaning that patients may have to travel less for biopsies.

Magtrace is a non-radioactive, dark brown liquid that is both a magnetic marker and a visual dye. It is injected into the tissue around a tumour, and the particles are then absorbed into the lymphatic system before becoming trapped in sentinel lymph nodes.

Sentimag, a magnetic sensing probe, emits sounds of varying pitches as it passes over the Magtrace tracer in a similar way to a metal detector. The nodes also often appear dark brown or black, which helps with identification. The surgeon can then remove the node for biopsy. If cancer cells are detected by a pathologist the surgeon may remove additional lymph nodes, either during the same procedure or at a follow-up.

Detection rates

Magtrace costs £226 (€266; $277) per unit excluding VAT, and the Sentimag probe costs £24 900. However, NHS trusts that commit to buying 100-120 units of Magtrace a year receive the Sentimag system free of charge. NICE has concluded that the technology is likely to be cost saving, but it recommends further data collection to monitor the number of additional sentinel lymph node biopsies done after the technology is adopted.

The current recommended treatment option for locating sentinel lymph nodes is a combination of a radioactive isotope trace and blue dye. However, this means that some patients have to travel to a different hospital with a radiopharmacy department to have the isotope injected, usually the day before they have surgery. The blue dye is also associated with a risk of anaphylaxis.

Evidence presented to NICE’s medical technologies appraisal committee has shown that Magtrace and Sentimag are likely to be as effective as the radioactive isotope with or without blue dye, with detection rates of 89.7% to 100% (Magtrace and Sentimag) and 83.3% to 100% (radioactive isotope).

Because Magtrace is not radioactive it can be used without the need for nuclear medicine safety procedures and facilities. It can also be injected as much as 30 days before surgery, whereas the radioactive trace can be given no more than 24 hours before the sentinel lymph node biopsy procedure.

The main adverse event associated with Magtrace is skin staining. Future magnetic resonance imaging (MRI) scans can also be affected, so its use should be considered carefully in people who are likely to need follow-up MRIs, said NICE.

The draft guidance is now open to public consultation until Thursday 16 June 2022.