FDA OKs Sentimag System for Detecting Lymph Nodes in Breast Cancer

Roxanne Nelson BSN, RN

July 24, 2018

The US Food and Drug Administration (FDA) has granted approval for the Magtrace and Sentimag Magnetic Localization System (Endomagnetics), a magnetic device system for guiding lymph node biopsies in patients with breast cancer undergoing mastectomy.

Also known as the Sentimag System, it uses magnetic detection during lymph node biopsy to identify sentinel lymph nodes for surgical removal.

"Sentinel lymph node biopsies are crucial for determining whether a patient's breast cancer has spread and helping the provider determine the most appropriate course of treatment," said Binita Ashar, MD, director of the Division of Surgical Devices in the FDA's Center for Devices and Radiological Health, in a statement.

"Currently, a sentinel lymph node biopsy is performed after injection of radioactive materials and/or blue dye," Ashar explained. "This magnetic system we're approving today will offer patients undergoing mastectomy an option for their sentinel lymph biopsy procedure that does not require the injection of radioactive materials."

According to the manufacturer, their technology uses a magnetic tracer (Sienna+) instead of the radioactive tracer and blue dye, and an ultrasensitive hand‐held magnetic probe (Sentimag) instead of a gamma probe. They note that this is the only solution that avoids the use of radioisotopes but instead manages to maintain standard working practice and provide equivalent detection rates to the standard of care.

The Sentimag uses the principle of magnetic susceptometry and generates an alternating magnetic field that transiently magnetizes the iron oxide particles in Sienna+ and then, in turn, the tiny magnetic signature generated by the Sienna+ particles is detected by the Sentimag probe. The system is suitable for use both pre- and postincision.

The FDA based their approval on results from a clinical trial that included 147 breast cancer patients and compared the Sentimag System with the control method of injecting patients with blue dye and radioactive materials and using a gamma probe to identify the sentinel lymph node. The rate of lymph node detection for the Sentimag System was 94.3% compared with 93.5% for the control group. Overall, virtually all patients (98.0%) had the same rate of detection with both methods.

The most common adverse events reported with the Sentimag System included breast discoloration, which generally faded after 3 months in mastectomy patients, bradycardia, and potential allergic reactions to the magnetic materials.

The Sentimag System is contraindicated for any patient with a history of hypersensitivity to iron oxide or dextran compounds, and it is also not recommended for those with iron-overload disease or with a metal implant in the axilla or in the chest.

The FDA notes that Magtrace may travel to other areas of the body including the liver or spleen if it is injected directly into the bloodstream. In these cases, Magtrace could cause image artifacts during MRI, although residues have not been reported to produce artifacts that would affect imaging during x-rays, PET scans, CT scans, PET/CT scans, or ultrasound studies.

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