Lymph nodes act as filters that capture viruses, bacteria, and abnormal cells such as cancer cells. When removing breast cancer, surgeons must decide which lymph nodes to biopsy, remove, or preserve. Removing the right ones helps make sure all the cancer is eliminated, while preserving unaffected nodes can reduce complications like lymphedema.

“Existing tools can show where lymph is draining but can’t reliably indicate whether a particular lymph node is involved with cancer while the operation is underway,” said the research team leader Viktor Gruev from the University of Illinois at Urbana-Champaign. “This can lead to overtreatment, undertreatment, or the need for a second procedure later.”