Magnetic Device System for Guiding Sentinel Lymph Node Biopsies Approved by FDA for Some Patients with Breast Cancer


he FDA has approved a magnetic device system for guiding lymph node biopsies in patients with breast cancer undergoing mastectomy.

The FDA has approved a magnetic device system for guiding lymph node biopsies in patients with breast cancer undergoing mastectomy. Endomagnetics’ Magtrace and Sentimag Magnetic Localization System (Sentimag System) uses magnetic detection during sentinel lymph node biopsy procedures to identify specific lymph nodes, known as sentinel lymph nodes, for surgical removal.

Binita Ashar, MD, director of the Division of Surgical Devices in the FDA’s Center for Devices and Radiological Health (CDRH) said, in a press release, the approved magnetic system will offer patients undergoing mastectomies an option for their sentinel lymph biopsy procedures that does not require injection of radioactive materials.

“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 Ashar, in a press release. “Currently, a sentinel lymph node biopsy is performed after injection of radioactive materials and/or blue dye.”

The Sentimag System is comprised of a sensitive magnetic sensing probe and base unit designed to detect small amounts of Magtrace, the magnetic tracer drug that is injected into breast tissue. The Magtrace particles travel to lymph nodes and become physically trapped in them, facilitating magnetic detection of the lymph nodes. Following the injection of Magtrace, the Sentimag probe is applied to the patients’ skin in areas closest to the tumor site containing the lymph nodes. The sensing of the magnetic particles is indicated by changes in audio and visual alerts from the base unit, enabling the surgeon to move the hand-held probe around the area of the lymph nodes, and locate the sentinel lymph node or nodes (if there are more than one). The surgeon then makes a small incision and removes the node, which is checked by a pathologist for the presence of cancer cells.

The FDA evaluated data from a trial of 147 patients with breast cancer to compare the Sentimag System to the control method of injecting patients with blue dye and radioactive materials together, and using a gamma probe to identify the sentinel lymph node. Patients were administered both methods to compare lymph node detection rates. The lymph node detection rate for the Sentimag System was 94.3% while the control method detection rate was 93.5%. Overall, 98% of patients had the same detection rate with both the Sentimag System, and the control method.

The most common adverse effects reported during the trial included breast discoloration, which is reported to disappear after 3 months in patients who underwent mastectomy; cardiac disorder; and potential allergic reaction to the magnetic materials. The Sentimag System is contraindicated in any patient with hypersensitivity to iron oxide or dextran compounds, and it is also not recommended for patients with iron overload disease or with a metal implant in the axilla or in the chest.

According to the FDA, Magtrace may travel to regions away from the injection site, such as liver or spleen, if injected directly into the bloodstream. In such cases the presence of Magtrace may cause image artifacts during Magnetic Resonance Imaging (MRI). Magtrace residues have not been reported to produce artifacts affecting imaging in X-ray, positron emission tomography (PET) scans, computed tomography (CT) scans, PET/CT scans or ultrasound studies.


FDA approves magnetic device system for guiding sentinel lymph node biopsies in certain patients with breast cancer [news release]. Silver Spring, MD; July 24, 2018: FDA website. Accessed July 24, 2018.

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