FDA Approves Magnetic Device System for Guiding Sentinel Lymph Node Biopsies in Patients With Breast Cancer


The U.S. Food and Drug Administration (FDA) recently approved a magnetic device system for guiding lymph node biopsies in patients with breast cancer undergoing mastectomy. The Magtrace and Sentimag Magnetic Localization System uses magnetic detection during sentinel lymph node biopsy procedures 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 (CDRH). “Currently, a sentinel lymph node biopsy is performed after injection of radioactive materials and/or blue dye. This magnetic system we’re approving … will offer patients undergoing mastectomy an option for their sentinel lymph biopsy procedure that does not require the injection of radioactive materials.”

How the Device Works

The Sentimag System uses magnetic materials to guide the sentinel lymph node biopsy procedure. The system comprises 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. The surgeon then makes a small incision and removes the node, which is checked by a pathologist for the presence of cancer cells.

Trial Results

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%, whereas the control method detection rate was 93.5%. Overall, 98.0% of patients had the same detection rate with both the Sentimag System and the control method.

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

Magtrace may travel to regions away from the injection site, such as the liver or spleen, if injected directly into the bloodstream. In such cases, the presence of Magtrace may cause image artifacts during magnetic resonance imaging. 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.

The FDA reviewed the Sentimag System application using a coordinated, cross-agency approach. The clinical review was conducted by the CDRH in consultation with the Center for Drug Evaluation and Research and with support from the Oncology Center of Excellence, while all other aspects of review and the final product approval determination was conducted by the CDRH.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.