The FDA approved Endomagnetics' magnetic tracer injection and detection system for guiding lymph node biopsies in patients with breast cancer undergoing mastectomy. In the procedure, the clinician injects a solution of dextran-coated iron oxide magnetic nanoparticles (Magtrace) in the viscinity of the tumour or the areola, as is done typically with dye or radioactive tracers. The Magtrace then clears along lymphatic vessels and labels the sentinel and draining lymph nodes by accumulating in specific cell types.
The surgeon can then detect these labelled lymph nodes using the Sentimag Magnetic Localization System’s handheld wand and base unit, which displays audio and visual feedback. These labelled lymph nodes are biopsied and removed.
Then, analysis of these biopsies for cancer cells can determine the extent of the breast cancer and metastatic burden. Magtrace is beneficial over the standard radioactive tracers by sparing patients from injection with radioactive materials, and for safety and ease of use for clinicians.
In a head-to-head clinical trial of 147 breast cancer patients undergoing mastectomy comparing the Sentimag System to a control dual tracer method using blue dye and radioactive contrast, the Sentimag System performed equally well as the control method.
It detected 94.3% of lymph nodes, while the control method detected 93.5%. 98% of patients had the same detection rates with both measurements. Side effects included temporary breast discoloration, bradycardia, and allergic reaction to the magnetic materials.
Sentinel and tumour draining lymph nodes are the first likely site of metastatic spread from the tumour. Testing these high-probability sites for existence of cancer cells helps to inform the patient and healthcare team about whether the cancer has spread to other parts of the breast or not to guide optimal care after mastectomy.