Women with invasive breast cancer could be injected with a magnetic marker liquid to tell doctors if their disease has spread, according to a recommendation by the government’s health advisers. The substance, called Magtrace, has been shown to locate the presence of sentinel lymph nodes, which show if the cancer has progressed beyond the breast. The National Institute for Health and Care Excellence (Nice), which advises ministers and the NHS on which treatments represent value for money in England and Wales, has issued draft guidance endorsing the use of Magtrace in conjunction with a probe called Sentimag. Magtrace is a non-radioactive brown liquid that acts as a magnetic marker and visual dye. It is injected into the tissue around a cancerous tumour in the breast. Particles are absorbed into the lymphatic system, follow the route that cancer cells are most likely to take when they spread from the original site of the disease and become trapped in sentinel lymph nodes. Once inside the patient, its progress is tracked using the Sentimag probe. It emits sounds of different pitches as it moves over the skin when it passes over the Magtrace, similar to the way a metal detector locates metal objects in the ground. Once the sentinel lymph node has been located, surgeons remove it and undertake a biopsy during which a pathologist checks if any signs of cancer are present. If so, they may carry out further surgery to remove more lymph nodes. Nice has recommended the procedure as an alternative to the existing way of identifying breast cancer that has spread, which involves the injection of radioactive isotopes and a blue dye. “People with breast cancer want to know if their cancer has been isolated or has spread to the rest of their body. The earlier this is established, the better the potential outcomes will be,” said Jeanette Kusel, Nice’s acting director for medical technology and digital. The agency said adoption of the system would help the NHS reduce its reliance on radioactive isotopes, which are imported, and enable any hospital to offer it, not just those with nuclear medicine facilities to use isotopes, which may make care more convenient for patients. The health and social care secretary welcomed Nice’s decision. “This promising research could provide a new tool for our scientists to track and slow the spread of breast cancer, the most common cancer in the UK,” Sajid Javid said. “We are always on the lookout for innovative treatments to speed up diagnosis and improve survival rates and we will outline more in our 10-year cancer plan, due this summer”.” But Nice warned Magtrace could produce side-effects and adverse events. These include the staining of a patient’s skin and their ability to have an MRI scan in future, and “so use of Magtrace should be considered carefully for people who are likely to need follow-up MRI studies”.