Magnetic device helps detect breast cancer during biopsies

The U.S. Food and Drug Administration has approved a magnetic device system for guiding lymph node biopsies in patients with breast cancer undergoing mastectomy. The Magtrace and Sentimag Magnetic Localization System (Sentimag System) uses magnetic detection during sentinel lymph node biopsy procedures to identify sentinel lymph nodes, for surgical removal.

Sentinel lymph nodes are the first lymph nodes to which cancer cells are most likely to spread from a primary tumour. For patients with breast cancer, testing the sentinel lymph nodes indicates whether the cancer has spread from the breast. A sentinel lymph node biopsy is used to identify, remove and examine lymph nodes to determine whether cancer cells are present.

The Sentimag System uses magnetic materials to guide the sentinel lymph node biopsy procedure. The 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. Following the injection of Magtrace particles they travel to lymph nodes and become physically trapped in them, the Sentimag probe is applied to the patients’ skin in areas closest to the tumour site. 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 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 percent while the control method detection rate was 93.5 percent. Overall, 98.0 percent of patients had the same detection rate with both the Sentimag System and the control method.

Binita Ashar, M.D., director of the Division of Surgical Devices in the FDA’s Center for Devices and Radiological Health (CDRH) said,  “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. Currently, a sentinel lymph node biopsy is performed after injection of radioactive materials and/or blue dye. 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.”