Cancer Invasion Identified with Surgical Fluorescence Technique

A new study describes a technique that will allow intraoperative detection of lymph node cancer metastases, so that healthy tissue can be preserved.

Researchers at the University of California, San Diego (UCSD; USA) have developed injectable fluorescently labeled molecules, which have been termed ratiometric activatable cell-penetrating peptides (RACPP). When used in mouse models, the peptides allowed surgeons to see where the cancer had spread with high sensitivity and specificity, even when the metastatic sites were only a few millimeters in size. The new technique could decrease time under anesthesia, since the surgical team need not wait for pathology reports, as well reducing unnecessary surgery on noncancerous lymph nodes.

This form of “instant pathology” is an important improvement over traditional sentinel node mapping, whereby only the location of the lymph node is detected, without gleaning any information on actual cancer involvement. Additionally, current methods for managing prostate cancer and neck squamous cell carcinoma, for example, only reveal the extent of cancer involvement after the patient has undergone surgical removal of all susceptible lymph nodes. The study was published in the January 15, 2012, issue of Cancer Research.

“With molecular-targeted imaging, surgeons can avoid unnecessary removal of healthy lymph nodes which is better long-term for patients,” said lead author associate Professor Quyen T. Nguyen, MD, PhD, director of the facial nerve clinic at UCSD Health System. “The range of the surgeon's visual field is greatly enhanced by a molecular tool that can help achieve accurate surgical margins and detection of metastases so that no tumor is left behind.”

Lymph nodes, located throughout the body, serve as biologic filters that contain immune cells to fight infection and clean the blood. When cancer cells break away from a tumor, the cells can travel through the lymph system; sentinel node surgery allows the surgeon to remove the nodes to determine cancer spread. Human nodes, however, are only half a centimeter in size, and are difficult to discern among the surrounding tissue during surgery. Furthermore, even when surgeons are able to map the location of the nodes, there is no current technique that indicates whether the lymph nodes contain cancer, requiring removal of more lymph nodes than necessary.

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