The Magnetic Approach

The main method of sentinel node biopsy in use today involves a radioactive tracer and a gamma-ray detector. While effective, this method comes with significant problems. Firstly, the method is limited by the supply of a substance called molybdenum-99, which decays so quickly that it must be supplied to hospital nuclear medicine departments every week, and which is made in just a handful of nuclear reactors worldwide.

Secondly, the handling of radioactive materials is subject to stringent regulations, requiring special staff training and segregation of the waste from the operating theatre. Thirdly, the cost to the hospital of providing and handling the radioactive materials is high. Consequently, in all countries, the majority of women with breast cancer will never be offered sentinel node biopsy based on this method. In contrast to the radioactive tracer, a typical magnetic tracer has a shelf life of several years. There are no staff safety issues, and therefore no regulatory burden. It is also much cheaper for the hospital than the radioactive tracer, and is therefore accessible to all.

The magnetic tracer is 99% water, but suspended in it are trillions of tiny particles of iron oxide, each far smaller than a human cell. This preparation is non-toxic, and is easily broken down and eliminated from the body. It has been medically licensed for more than 20 years, is approved for use worldwide, and is often used on people who are having MRI scans.