New technique spots how far cancer has spread

Last Updated: Jan 13, 2013, 13:25 PM IST

Washington: Researchers have developed a new technique that will allow surgeons to identify how far the tumour has spread and help them decide which tissue to remove in order to save healthy cells in cancer patients.

"With molecular-targeted imaging, surgeons can avoid unnecessary removal of healthy lymph nodes which is better long-term for patients," said Quyen T Nguyen, associate professor at University of California, San Diego School of Medicine.

"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 tumour is left behind," Nguyen said in a statement.

Lymph nodes, located throughout the body, serve as filters that contain immune cells to fight infection and clean the blood. When cancer cells break away from a tumour, the cells can travel through the lymph system and hide in these tiny organs.

Surgeons remove the nodes to determine if a cancer has spread. However, human nodes, only half a centimetre in size, 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 or not the lymph nodes contain cancer, requiring removal of more lymph nodes than necessary.

"This research is significant because it shows real-time intra-operative detection of cancer metastases in mice.

"In the future, surgeons will be better able to detect and stage cancer that has spread to the patient`s lymph nodes using molecules that were designed and developed at UC San Diego," Nguyen said.

The fluorescently labelled molecules, known as ratio-metric activatable cell-penetrating peptides (RACPP), are injectable.

When used in mouse models, surgeons could see where the cancer had spread with high sensitivity and specificity even when the metastatic sites were only a few millimetres in size.

This form of instant pathology is an improvement over traditional sentinel node mapping, whereby only the location of the lymph node is detected without gleaning any information on actual cancer involvement.

Current methods for managing prostate cancer and neck squamous cell carcinoma only reveal the extent of cancer involvement after the patient has undergone surgical removal of all susceptible lymph nodes.